Advanced Glaucoma

Management Pearls

Abstract

A significant proportion of glaucoma patients present late, particularly in the developing world, and unfortunately, in an advanced stage of the disease. They are at imminent danger of losing remaining vision, and may also be afflicted with various socioeconomic and health challenges. The encounter with such a patient is typically characterized by anxiety/fear and sometimes hopelessness from the patient's perspective. The physician may also feel that they are in a difficult position managing the patient's disease. When dealing with such cases, we suggest a holistic, individualized approach taking into account the ‘biopsychosociospiritual’ (BPSS) profile of each patient. The BPSS model takes into account relevant ocular as well as systemic biology (factors such as the mechanism of glaucoma, level of intraocular pressure [IOP], rate of progression, life expectancy, general health), psychological considerations (e.g., fear, depression), socio-economic factors and spiritual/cultural values and beliefs before being able to decide with the patient and their care partner(s) what treatment goals should be and how they can best be approached. Treatment for advanced glaucoma can be highly effective, and patients and their care partners should be informed that aggressive IOP lowering to the low teens or even single digits offers the best chance of protecting remaining vision. This can be achieved safely and effectively in most cases with trabeculectomy (including an antimetabolite), and in some cases with medical and/or laser therapy. Vision rehabilitation and psychosocial support should also be considered in order to optimize remaining vision, replace fear with hope as appropriate, and thus improve the overall quality of life.

INTRODUCTION

Patients with advanced glaucoma (AG), here defined as near total cupping of the optic nerve with or without severe visual field (VF) loss within 10° of fixation, i.e. scotoma encroaching on or splitting fixation,¹² [Figure 1] tend to have a worse visual and overall prognosis. They are at imminent danger of losing remaining vision, and may also have various socioeconomic and health challenges such as stigmatization, unemployment or underemployment, morbidity/mortality, increased risk for driving accidents, falls, as well as mental health difficulties including depression. The encounter with such a patient is typically characterized by anxiety or fear and sometimes hopelessness from the patient's perspective. The physician may also feel that they are in a difficult position managing the patient's disease.

Figure 1: (a) A photo of optic nerve with advanced damage. (b) A corresponding advanced visual field defect with HVF, 24-2 strategy. (c) A corresponding advanced visual field defect with HVF 10-2 strategy, size III

Lowering the intraocular pressure (IOP) to the low teens or even the upper single digits and reducing IOP fluctuation has the strongest evidence of protecting the optic nerve and remaining VF³⁴ other strategies such as enhancing blood flow and neuroprotection may be helpful but lack a solid evidence base.

This paper offers management pearls for patients with AG, including tips for glaucoma surgery, emphasizing the importance of aggressive IOP lowering as well as providing psychological and other support as needed for the patient. We prefer the expression “advanced glaucoma” instead of ‘end stage glaucoma’ because the latter has a connotation of hopelessness.

PATHOPHYSIOLOGY AND EPIDEMIOLOGY

Patients with AG have in common advanced disc and/or VF changes that represent a final common pathway for one or more mechanism(s). The most common type of glaucoma worldwide leading to advanced damage is primary open angle glaucoma, but other causes alone or in combination may also be present. These include exfoliation syndrome and angle closure, depending on the population and patient profile.

There is scarcity of data that adequately documents the prevalence of AG in the general or glaucomatous population. According to a clinic based study in UK, 48/126 (38%) of newly diagnosed glaucoma patients were in the advanced stage.⁵ In glaucoma prevalence survey in rural South Africa, it is found that 45% of those with glaucoma were blind in at least one eye.⁶

Jay and Murdoch estimated the average time to progress from the earliest identifiable stages of VF loss to advanced disease (absolute scotoma within 5° of fixation). For untreated disease, the average time to develop advanced disease depended on level of IOP: 14.4 years for IOP 21-25 mm Hg, 6.5 years for IOP 25-30 mm Hg and 2.9 years for IOP > 30 mm Hg. The interval to progress from 1^st detectable field loss to advanced disease was 3.6 years for IOP greater than 25 mm Hg.⁷

RELEVANCE TO SUB-SAHARAN AFRICA (SSA)

It is known that African descent is associated with a higher risk of developing aggressive glaucoma, with an earlier age of onset.⁸ The course of glaucoma is rapidly progressive and unfortunately, black patients are also more likely to go blind than Caucasian patients.⁹ Most patients in SSA, particularly in rural areas, tend to present late in the advanced stage of disease or with unilateral blindness; exfoliation and angle closure appear to be common mechanisms in some SSA countries although population based data on the prevalence of various glaucoma types is lacking. In addition, management is challenging in that medications may be unavailable, unaffordable, and compliance to medication as well as follow-up may also be very poor. There are also a variety of social and cultural factors specific to the situational context (e.g., belief that blindness is due to fate and cannot be changed, seeking out village based traditional care, difficulty accessing specialized care) that need to be considered in the management of these patients. The holistic approach to glaucoma care and attention to trabeculectomy technique described in this paper will be highly relevant for practicing ophthalmologists in this region.

CLINICAL EVALUATION AND FOLLOW-UP

Assessment of risk factors for progression

Preventing progression from earlier stages to AG is certainly a worthy goal. Although the rate of progression (or severity of disease) can be estimated to some extent based on how the patient has been doing to date,¹⁰ it is important to recognize which patients are at high risk for progression and then take more aggressive steps in order to slow or arrest the course of the disease. Being African and having advanced VF loss are both associated with worse prognosis.⁹ These and other factors are summarized in Table 1.¹¹¹² Although not mentioned in most studies, poor compliance¹³ as well as low socioeconomic status also herald a poor prognosis.

Table 1: Risk factors for progression in advanced glaucoma

DETECTING PROGRESSION AND LONG-TERM FOLLOW-UP

Unlike glaucoma in the early/moderate stage, patients with AG are symptomatic and as the field loss increases, they may notice increased functional impairment. It is important to question which activities patients are currently involved in, and whether they have changes in undertaking these activities with time. Knowledge of their degree of involvement in mobility, driving, reading, and spotting distant and near objects is important to detect any changes with time and to guide decisions regarding treatment and rehabilitation. Patients who are monocular or who are good observers are often acutely aware of any functional impairment. It is therefore helpful to ask patients at every visit “Is your vision changing, and if so in what way?” Trying to discriminate between whether the VF is ‘closing in’ versus an ‘overall blur’ (which may represent media opacity such as cataract) can often be helpful to get a subjective sense of stability or progression. See Table 2 for important parameters to monitor in the follow-up of AG.

Table 2: Important clinical parameters for detecting progression and long-term follow-up of patients with AG

On examination, attention should also be given to identification of secondary causes of glaucoma (neovascularization, uveitis etc.) and presence of any angle closure so that other treatment strategies can be employed as necessary. Gonioscopy and a dilated exam (if safe to dilate) are therefore, important parts of the patient workup. Dilation will assist in identifying subtle cases of exfoliation syndrome, permit a more detailed stereoscopic examination of the nerve, and also permit one to conduct a good peripheral retinal exam to rule out peripheral neovascularization, inflammation etc.

Due to the severe neuroretinal rim loss in AG, it is often difficult to assess changes in the optic disc structure over time and also to correlate VF changes with nerve alterations. Therefore, optic disc examination is less useful than assessment of functional change in this stage of glaucoma.¹⁴ However, any remaining neuroretinal rim should be documented and examined carefully at each visit as well as making note of a disc hemorrhage which typically signifies ongoing damage/progression. The most important part of the disc to assess is the temporal portion, which has fibers from the papillomacular bundle that subserve the central VF and therefore, central visual acuity. Observers should therefore, pay particularly close attention to the temporal disc and carefully documenting any remaining rim in this area. Optic nerve head and retinal nerve fiber layer (RNFL) imagers are helpful in early and moderate stages of glaucoma but seem less helpful in AG. Given the degree of tissue loss, in patients with AG it may be difficult to differentiate neuroretinal rim or RNFL thickness change related to glaucoma from noise in measurements.¹⁵ Some studies have demonstrated a correlation between macular thickness measured with time-domain optical coherence tomography and VF mean deviation,¹⁶ but this does not appear to have been widely utilized in the follow-up of patients with AG.

VF changes may be the most important or the only evidence for progression in AG. Since most patients have a central island of vision that is spared or split at this stage, a central VF program e.g., Humphrey 10-2 with a size III stimulus may be useful either as a replacement for or in conjunction with a 24-2 or 30-2 program.¹⁷ In patients who have difficulty with size III stimulus VFs, the use of a larger size V is also helpful to detect changes over time. Carefully examining the cardinal points around fixation, as well as quadrant totals [Figure 2] which are easily available from a 10-2 size V printout can be helpful in gauging threat to fixation as well as progression.

Figure 2: Central 10-2 HVF in a patient with advanced glaucoma (unrelated to case in Fig. 1). The field was generated with a SITA standard method using a size V stimulus. Note quadrant totals on the bottom right hand portion which can be used to monitor sequential fields for progression

We suggest patients with AG that appear stable should be followed frequently, at least every 3-4 months, and if unstable (i.e., target IOP not achieved or clear evidence of structural and/or functional progression) then more frequently as needed.

MANAGEMENT OF AG

BIOPSYCHOSOCIOSPIRITUAL (BPSS) PROFILE OF EACH PATIENT

Apart from focusing on aggressive IOP reduction, the optimal approach to manage an individual patient with AG will depend on a holistic, customized approach to care that takes into account various components of health. To capture this approach, we utilize the term BPSS profile, which we have modified from Engel's original biopsychosocial model.¹⁸ The BPSS model takes into account relevant ocular as well as systemic biology (factors such as the mechanism of glaucoma, the level of IOP, rate of progression over time, life expectancy, general health such as asthma and cardiovascular disease, which may affect the choice of therapy), psychological considerations (e.g., fear, depression), socioeconomic factors (e.g., cost effectiveness, social support or lack thereof) and spiritual/cultural values and beliefs (e.g., perspectives on alternative or complementary therapies) before being able to decide with the patient and their care partner(s), what treatment goals should be and how they can best be approached.

After evaluation of the BPSS profile of the patient and discussion with the patients regarding the pros and cons of all management options, a reasonable approach can be selected. During the course of the discussion with the patient and their care partner, it is important to be realistic about expectations (e.g., one can hope to maintain vision in most cases rather than improve it, and that vision may get worse with trabeculectomy surgery before it gets better; however, if combining with cataract surgery there may be some hope for improvement.) In some situations, if subnormal low pressure is achieved, vision may improve or vision loss may progress for unknown reasons); it is also essential to replace fear with hope as appropriate.¹⁹ As physicians, we must not leave the patient with the message that nothing can be done – for even if the patient loses all vision, they may still be able to enjoy a reasonable quality of life (QOL) depending on their sense of self, utility of other senses, support system available etc.

AGGRESSIVE IOP LOWERING

The only proven treatment in preserving the visual function in glaucoma is by control of IOP. Patients with AG can do reasonably well in terms of protecting remaining VF and QOL if their IOP is very low (low teens or even high single digits). In the advanced glaucoma intervention study (AGIS), patients that did not progress had a mean IOP of 12 mm Hg.³ Odberg²⁰ also demonstrated that a very low IOP was needed in order to maintain visual function in AG over a long period of time.

In addition to the absolute number of the IOP reduction, a treatment option should also reduce the IOP peak, diurnal (short-term fluctuation) and long-term changes (visit to visit fluctuation). According to the AGIS study, long-term visit to visit fluctuation is most significantly associated with VF progression in those with lower mean IOP range. These fluctuations should be considered whenever a patient with apparently lower office measurement of IOP demonstrates progression of the disease. In those patients at risk of having IOP peaks outside office visits, a diurnal tension curve should be considered. Many studies have found that surgical treatment is associated with consistently lower level of IOP, with lesser amount of short-term and long-term IOP fluctuation.²¹

MODE OF MANAGEMENT

The traditional management paradigm of trying various medical therapies to lower IOP then moving on to laser trabeculoplasty (LTP) and finally filtration surgery, based on failure to control the IOP or evidence of progression at each stage, typically does not apply to this group of patients.

Patients with some impairment of activities of daily living (ADL) may have difficulty with medical management and require considerable support from care partners or home care services. Therefore, consideration of the visual and overall function of the patient with AG is very important before a decision is made regarding the preferred mode of therapy – medical, laser or surgical.

Since a randomized clinical trial comparing the outcomes of medical, laser and surgical interventions in AG is lacking, there is no uniformly accepted best treatment option in this group of patients. A recent National Institute for Health and Clinical Excellence guideline of UK has recommended that patients who present with AG should be offered primary glaucoma surgery,²² while King et al. have argued that the current evidence is not supportive of this recommendation.²³ A Cochrane review of medical versus surgical interventions for open angle glaucoma concluded that there was insufficient evidence to determine how well recently available medications work compared with surgery in more severe OAG, and which approach is the cost-effective option.²⁴

MEDICAL THERAPY

In patients who are progressing slowly and may have longevity such that they may not go blind during their lifetime, and who can afford it, medical therapy may be an appropriate option. In this regard, the use of simple modifications can enhance the success of treatment. Instructing and observing the way patients apply the medications is important. Compliance to the prescribed medication should be always considered in this group of patients as studies have shown that patients who were less adherent were significantly more likely to have worse VF defect severity.²⁵ Due to their visual status, AG patients may rely more heavily on others for assistance with drop instillation. One should therefore, ensure that all care partners (individuals who are stakeholders in the care of the patient) are aware of the proper use of the drops by the patient. The least amount of medication(s) with the most likelihood of lowering the IOP while keeping costs minimal and causing no or minimal side effect should be selected. Prostaglandin analogues and combination of topical carbonic anhydrase inhibitors (CAI) and beta blockers are better associated with lower level of short term fluctuation when compared with beta blockers alone.²⁶ Antiglaucoma drugs like brimonidine and betaxolol have been reported to have neuroprotective effects by either stimulating the expression of neurotrophic factors or by their effect on the perfusion of the optic nerve, respectively, although the clinical utility of these findings remains to be proven through more robust study designs.²⁷²⁸

LASER TREATMENT

LTP with argon, diode or selective laser treatment has a significant role in the control of IOP to reduce the number of medications used by the patient or as an adjunct to medical therapy. It has lower rates of complications than incisional surgeries and the IOP reduction can be up to 30%.²⁹ This may be adequate for some patients with AG, but there are major concerns of immediate complications (such as high IOP spikes that could threaten fixation) and the concern of weaning of the effect with time, sometimes unpredictably such as in patients with exfoliation glaucoma. Overall, LTP is unlikely to achieve very low pressures in patients with AG and so is not discussed in detail in this paper. However, it has a role in selected patients that fail medical therapy and are not good candidates for surgery.

Owing to the risk of hypotony, vision loss and phthisis trans scleral diode cyclophotocoagulation (CPC) has generally been reserved for refractory glaucoma cases with poor visual prognosis. Some recent papers, however, show good results with the use of trans scleral CPC in eyes with good vision.^30–32 As a result of a more targeted approach to the ciliary processes, endoscopic CPC is associated with the fewer complications (vs trans scleral CPC) and appears to have a beneficial effect when combined with phacoemulsification.³³ However, to the best of our knowledge, there do not appear to be any published studies on the success of these laser treatments in patients with AG.

SURGICAL TREATMENT

In most cases, despite maximum medical and laser therapy, glaucoma filtration procedures are required for further IOP reduction and the prevention of VF loss.³⁴ Surgeries to control IOP in glaucoma that work on enhancing aqueous outflow pathways include (1) increase outflow by creating a new outflow channel (e.g., traditional trabeculectomy, Ex-PRESS glaucoma implant, aqueous drainage devices, and Fugo blade transciliary filtration); (2) augment the conventional (trabecular) outflow pathway (Fugo blade goniotomy, Trabectome, canaloplasty, excimer laser trabeculostomy, and trabecular micro-bypass stent); (3) increase uveoscleral outflow (e.g., SOLX Gold Shunt). The goal in these latter two groups is to lower IOP and decrease dependence on glaucoma medications while eliminating complications associated with external filtration. However, these newer surgeries do not appear to consistently achieve low IOP required for patients with AG, and more studies are needed with comparative designs and longer follow-up periods before their use in this group of patients can be advocated.³⁵

TRABECULECTOMY

Trabeculectomy surgery appears to be a long-term solution having the best outcome for IOP control. According to a recent study, trabeculectomy survival (IOP less than 21 mm Hg) at 20 years was approximately 60% with no topical medication and approximately 90% with additional topical medication; 7% and 15% of eyes had become blind by 10 and 20 years, respectively.³⁶

Trabeculectomy has also been reported to be associated with less diurnal IOP fluctuation, less marked peak IOP values and a lower mean diurnal IOP value in surgically treated patients compared to maximum medical therapy in patients with AG.²¹³⁷

However, surgery does carry with it higher short and medium term risk than simple medical or laser treatment (i.e., risk of endophthalmitis, suprachoroidal hemorrhage, hypotony, cataract formation, wipe or snuff out) but generally has good outcomes if combined with antimetabolites (5-FU or Mitomycin C - MMC). The techniques popularized by Moorfields (Safe surgery system) are worth considering in this regard.³⁸

Visual compromise in patients undergoing trabeculectomy may be attributable to cataract, cystoid macular edema, hypotony maculopathy, suprachoroidal or vitreous hemorrhage, retinal detachment, optic nerve damage, and uncontrolled IOP. Identification of high risk groups for complications and careful anticipatory planning can prevent some complications. However, loss of central vision can occur even after an otherwise uncomplicated operation, and this has been termed the “wipe-out” phenomenon. Wipe-out refers to an idiopathic, irreversible loss of central vision after surgery in glaucoma patients with advanced disease with reported incidence of 0-7%.³⁹⁴⁰ Although some patients (and surgeons) may be fearful of this complication, the risk of doing nothing is also very high in patients with AG and uncontrolled IOP, sometimes approaching 100%. The risk of severe complications therefore needs to be seen and balanced with the risk of inaction or under treatment.

Another important scenario is management of a patient with AG who has controlled or borderline controlled IOP and who also has a visually significant cataract. Combined surgery may be best suited for such group of patients as it is important to avoid pressure spikes post operatively and maintain long-term IOP control. For some patients on maximal medical therapy, cost is often an issue and this approach may reduce the financial burden by eliminating or reducing medications. An improved IOP reduction with combined surgery also benefits patients that have poor compliance with medications. A very reasonable option in this regard would be to consider combined cataract (phaco or manual small incision cataract surgery - SICS) with trabeculectomy and antimetabolite.¹⁴¹

If a cataract is not visually significant and if IOP is uncontrolled, we recommend performing trabeculectomy alone, in order to minimize the risk of severe complications such as suprachoroidal hemorrhage.¹

TRABECULECTOMY – SURGICAL TIPS

In some cases, there may be previous trauma or surgery that has left the superior conjunctiva scarred. Depending on the degree of scarring and also the thickness of the conjunctiva, one could consider repeat trabeculectomy or other approaches such as aqueous drainage device, CPC etc. One way to obtain an idea of conjunctival scarring is to examine the conjunctiva while it is being moved. This can be done by moving the lid from side to side while pressing on the globe with the patient looking downwards, or using a Q tip to move the conjunctiva after application of anesthetic drops. The discussion below is directed primarily at performing trabeculectomy when it is done for the 1^st time (i e., a primary trabeculectomy). As it is the mainstay of treatment in AG, we provide details hereunder about ways to prevent complications associated with this surgery in patients with AG [Table 3].

Table 3: Summary of pre-, intra- and post-operative considerations with trabeculectomy for a patient with advanced glaucoma

Pre-operative

The risks of any form of surgery should be explained to the patient in advance. In particular, it is vital to explain that surgery for glaucoma is usually done to preserve vision and will likely not improve vision (unless combined with cataract extraction). Several studies have demonstrated a loss of best-corrected visual acuity (of about 1 line) in post-operative patients, and it is essential that patients are aware of this. Patients with AG should be informed of the risks of “wipe out” of the remaining field, although as stated earlier this is rare.⁴²⁴³

The use of topical steroids pre-operatively may help reverse the histological changes in the conjunctiva associated with long-term use of anti-glaucoma drugs and improve outcomes of filtration surgery. Thus in patients who are on medications that create conjunctival hyperemia, starting low potency steroids (e.g., fluorometholone qid for a week) before the surgery can help improve the success rate.⁴⁴

The use of peri- and retrobulbar anesthesia for glaucoma surgery is associated with a subsequent rise of orbital pressure⁴⁵ which has been speculated to play a role in the wipe out syndrome. Adrenaline is associated with vasoconstriction which may also theoretically contribute to visual reduction from ischemia. The volume of adrenaline free anesthesia used should be kept to the minimum necessary, and the use of hyaluranidase, where accessible, can be considered to enhance the effect. Continuous orbital compression with balloons and other devices should be avoided as they can raise intraocular and intraorbital pressure considerably, with attendant risks of nerve and/or vascular compromise.

In our view, the optimal anesthetic route in AG, for patients who are cooperative, is topical/subtenons, which is as effective as retrobulbar anesthesia.⁴⁶ The use of topical, subconjunctival or subtenons, and intracameral injection of preservative free lidocaine has the advantage of reducing the risk of major anesthesia related complications mentioned above as well another rare but serious complication, brain stem anaesthesia; however, for patients who are extremely anxious or uncooperative (e.g., young age), peribulbar anesthesia with sedation, or general anesthesia may be required.

The IOP needs to be lowered slowly intra operatively in order to avoid a catastrophic suprachoroidal hemorrhage or to setup a cycle of aqueous misdirection in predisposed eyes. Pre-operative mannitol (0.5 mg/kg) or acetazolamide (po or iv) can be helpful in this regard. If the IOP is still high immediately pre-operatively, the eye can be decompressed slowly via a paracentesis.

Intraoperative modifications

There is a fine balance between the goal of achieving low IOP post-operatively and the risk of hypotony or hypertony and care should therefore be taken during each step of the procedure to avoid excessive drop or elevation of IOP. Several modifications to traditional techniques have been suggested to achieve this.

Fornix or limbus based surgeries can have equally good IOP outcome following trabeculectomy.⁴⁷ The relative advantage of one over the other should be utilized to minimize complications and maximize success. The limbus-based operation may be more likely to eliminate problems with post-operative leakage through the conjunctiva but may also give rise to a larger more limbal bleb. Our preference is to use the fornix based approach and aim for a low posterior bleb similar to the technique advocated by Dr. Peng Khaw in the Moorefields safe surgery system.³⁸ Scar tissue in the conjunctiva as well as the surgeons own preference may guide the choice of approach.

Aggressive healing response is a major concern particularly in African patients as it may compromise the outcome of trabeculectomy.⁴⁸ Intra- and post-operative use of anti-fibrotic agents (e.g., 5-Fluorouracil or Mitomycin C) as well as anti-Vascular Endothelial Growth Factor (VEGF) agents such as Bevacizumab⁴⁹ should be considered to reduce subconjunctival scarring and surgical failure. Specifically, Mitomycin C reduces the risk of surgical failure in eyes that have not undergone previous surgery or eyes at high risk for failure with surgery.⁵⁰ Studies from trabeculectomy on African patients have shown that intraoperative application of MMC is more efficacious than 5-FU in lowering IOP following primary trabeculectomy.⁵¹⁵² Antimetabolites should be placed diffusely and away from limbus to create a smooth bleb.

Every effort should be made to avoid hypotony intra-operatively as well as post-operatively. For example, toothed forceps, or even serrated forceps with indentations that are sharp enough to cut the conjunctiva, should not be employed to avoid conjunctival button holes. In this regard, grasping Tenon's capsule rather than conjunctiva is helpful.

Placement of temporal paracentesis track is crucial for intraoperative anterior chamber reformation and assessing flow through the fistula/flap complex; it can also assist in post-operative AC reformation with viscoelastic at the slit lamp or in the minor room if needed.

Care should be taken to maintain the AC throughout the procedure with BSS, viscoelastic or an anterior chamber maintainer as sudden shallowing and hypotony can also create a risk of suprachoroidal hemorrhage intra-operatively.

The scleral flap should be relatively thick so as to permit closure without excessive flow. Usually it is made at least half the thickness of the sclera. Flap closure should be reasonably tight to prevent immediate hypotony; intra-operative flow can be assessed by passing balanced salt solution through the side port and watching the flow through the flap; suture tension should be titrated so that there is some flap flow, but the AC remains formed and does not collapse during surgery. Sutures can also be preplaced in the scleral flap (once the flap is made and before entering the eye) to permit rapid closure. The use of sutures half thickness of the scleral flap reduces full-thickness holes through the flap that may allow excessive leakage. The amount of leakage is adjusted appropriately through the side port and sutures tightened or loosened accordingly. The use of a slip knot is helpful in achieving the desired level of tension of the scleral flap in a guarded filtration procedure. The application of releasable or laserable sutures makes possible adjustment of the IOP post-operatively.

Another practice we follow is to operate early in the morning in patients with AG so that the IOP and chamber can be checked 2-4 h later; in this way it is possible to detect and treat early post-operative spikes as well as detect and treat flat chambers.⁵³ Typical post-operative medications include antibiotics and corticosteroid eye drops. The type, strength and frequency of administration are dictated by the degree of inflammation, presence/absence of complications, and amount of filtration (function of the bleb). Cycloplegic eye drops (like atropine) may be administered at the conclusion of surgery, particularly if there is anticipation of shallow AC and/or instituted post-operatively, in the presence of significant inflammation or shallow AC.

BLIND PAINFUL EYE(S) WITH GLAUCOMA

An eye that has lost all vision and has uncontrolled pressure is sometimes referred to as having “absolute glaucoma”. In such situations, the mechanism of underlying pressure elevation may be apparent (e.g., neovascular or uveitic glaucoma), whereas in other cases, it may not. Once vision is lost, at present it cannot be regained. The focus of any management plan therefore needs to be on other goals (decided upon in close discussion with the patient). These could include a focus on maintaining vision in the fellow eye, psychological and other support, helping the patient to keep the affected eye comfortable, reasonable cosmetic appearance etc. Unfortunately, patients with absolute glaucoma may have pain which can adversely affect QOL. If pain is present, an attempt should be made to discern the etiology of the pain and treatment can then be directed accordingly, beginning with conservative management if appropriate. Common causes of pain include one or more of elevated pressure, inflammation, and bullous keratopathy. If high IOP is the main factor causing pain, then IOP lowering can be helpful either via medication or laser CPC. If inflammation is the issue, then anti-inflammatory medications along with cycloplegia can assist. If the pain is from corneal edema with bullous keratopathy therapy can be directed to the cornea (e.g., hypertonic saline, contact lens use, Gunderson flap) or to any underlying factor that may be worsening any remaining endothelial pump function. For example, simple measures like IOP lowering, management of inflammation or removing a topical CAI can result in improved pump function and corneal clarity.⁵⁴

If conservative measures do not result in improved comfort for the patient, then pain can be relieved with retrobulbar injection of chlorpromazine⁵⁵ or absolute alcohol. If this is not effective, or there is a cosmetic concern, then evisceration or enucleation can be considered with an ocular prosthesis as appropriate.

VISION REHABILITATION (VR) AND PSYCHOSOCIAL SUPPORT

The ultimate goal of a patient with AG is to maintain or improve their QOL. Vision-specific and general health-related QOL are adversely impacted in patients diagnosed with glaucoma. Problems with ambulation, reading, spotting, and glare can be major concerns.⁵⁶⁵⁷ Furthermore, QOL can be reduced due to the inconvenience, side-effects and/or cost of a treatment regimen. Limitations on social activities and dependence on others also further diminishes QOL.

VR is important in AG because it increases the patient's ability to function based on any remaining vision; it may also play a role in providing psychosocial support. Appropriate referral for this service, if available/accessible is crucial. VR maximizes an individual's visual potential, thus increasing their ability to function, with less likelihood of dependence on others for assistance with daily needs. Patients can maintain their acuity and their reading and near-point functioning with appropriate spectacles, and they can be provided with assistance for any peripheral field loss, glare, as well as advocate for and connect the patient to other support services as required.

Handheld magnifiers can be utilized for short periods of reading (to identify medication bottles, menus, phone books etc.) after determining the level of magnification needed. For longer periods of reading (books, magazines, newspapers) full-field microscopes and stand magnifiers are better options. Electronic magnification (e.g., via closed circuit television or devices such as the ipad) can also assist with short- and long-term reading tasks.⁵⁸ Items with large print permit patients to read more easily and improving the lighting condition of work or home environment is also generally helpful for most activities.

Patients can gain various travel skills by orientation and mobility training like the use of white or other color canes. Optical devices like sectoral prisms, high minus lenses, and reverse telescopes can assist glaucoma patients with severely constricted VFs to enhance mobility. For patients with scotomas near fixation, preferred retinal locus training can be helpful.⁵⁵

Psychosocial support should also be considered. Knowledge of how VF and acuity loss have impacted their lives as well as the fact that vision can only rarely be recovered once lost may be demotivating. This coupled with fear of losing the remaining vision, difficulty undertaking ADL, and increasing dependency on others may create anxiety and/or depression. Proper psychosocial and spiritual/cultural support for patients (with referral to skills and employment support services for individuals with special needs, and to psychologists and spiritual care services as needed) and replacing fear with hope as appropriate may be very helpful e.g., if appropriate, patients could be informed that not all patients with AG will go blind during their lifetime.

CONCLUSION

Patients with AG are at high-risk for going blind, and should be managed aggressively to protect remaining vision. Risk factors for progression of disease should be identified, and management titrated based on the risk of progression and target IOP. If the underlying pathophysiological process is known, an attempt should be made to treat underlying factors. Treatment for eyes with AG can be extremely effective, but only if IOP reduction is significant and sustained. Incisional surgery offers the best chance of achieving this, despite some risks. However, medical or laser therapy may be appropriate in some patients (e.g., those at high-risk of complications or slow rate of progression and unlikely to go blind during their lifetime). Vision rehabilitation (VR) with optical, lighting, mobility, and psychosocial support should be considered as needed in order to optimize remaining vision and thus improve overall QOL.

ACKNOWLEDGEMENTS

Drs. M. Bruce Shields, R. Rand Allingham, Leon W. Herndon, William N. White, II, and Mary Gina Trevasani inspired discussion of this topic during Dr. Damji's fellowship. We also thank Dr. Fisseha Ayele for helpful comments on the manuscript.