Coexistent visually significant cataract and glaucoma is a common clinical entity. Appropriate management is often a matter of controversy. Different modalities of treatment are available such as cataract and glaucoma surgery performed in two stages or a combined surgery performed in one sitting. It has been observed that over a period of time the intraocular pressure (IOP) control from the combined glaucoma filtering and cataract surgery ceases to be effective, thus necessitating additional anti-glaucoma medications. Besides the percentage of well formed blebs with the above procedure versus trabeculectomy alone has varied across studies. Additionally long-standing phacomorphic glaucoma is a unique condition where an IOL is implanted in an acutely inflamed eye. This decreases the chances of success of a filtering surgery.
We performed combined extracapsular cataract extraction (ECCE) with posterior chamber intraocular lens (PCIOL) implantation and primary implantation of Ahmed glaucoma valves (AGV) in 15 eyes (15 patients) of phacomorphic glaucoma with almost 360° peripheral anterior synechiae. The surgery was done in an attempt to maximize the visual restoration and IOP control postoperatively.
Materials and Methods
We performed a retrospective analysis of the medical records of 64 patients diagnosed with phacomorphic glaucoma, who presented between January 1995 and January 1999 (48 months) at the Glaucoma Services, Guru Nanak Eye Centre, New Delhi. Fifteen patients had received ECCE, PCIOL implantation and primary implantation of AGV. Patients with phacomorphic glaucoma were diagnosed as those having angle closure in one or both eyes secondary to intumescence of the crystalline lens as assessed by measurement of the anteroposterior lens thickness, the anterior chamber depth and the anterior chamber angle (angle closure). The lens thickness and anterior chamber depth was assessed with the help of ultrasonography.
For each patient, the following details were gathered: age; gender; duration of phacomorphic attack; preoperative visual acuity and IOP; detailed slitlamp examination of the affected and fellow eye; gonioscopy of both eyes with Goldmann's single mirror gonioscope and the Zeiss four mirror gonioscope; number of preoperative medications (both systemic and local) used to control IOP; ultrasonography for lens thickness and anterior chamber depth in both eyes and for posterior segment evaluation whenever ophthalmoscopic examination was not possible; postoperative evaluation of visual acuity at 3 months and 6 months; postoperative IOP in the first week after surgery, and subsequently at 3 months, 6 months, 12 months and more depending upon the duration of follow-up of the patients. A minimum follow-up of 6 months for all patients was determined as a criterion for inclusion in this study. The number of postoperative medications used and the average duration of use after surgery; postoperative optic disc evaluation and visual field changes; and early and late complications of surgery were also documented.
Exclusion criteria included patients with types of lens-induced glaucomas besides phacomorphic glaucoma, patients with uveitis and complicated cataract or patients with inaccurate projection of rays preoperatively. Patients with primary glaucomas with cataract were also excluded.
All patients received systemic prednisolone (0.75 mg/kg/ day) and a topical antibiotic- corticosteroid combination (fluoromethalone and neomycin) in addition to the antiglaucoma medications. The surgical procedure was similar in all cases. The AGV was inserted between the superior rectus and the lateral rectus muscle in the superotemporal quadrant of the eye beneath a fornix-based conjunctival flap. The AGV was irrigated with balanced salt solution to prime the valve mechanism. The implant body was placed 10 mm posterior to the corneoscleral limbus and sutured to the sclera with 9-0 nylon sutures. A rectangular partial thickness scleral flap measuring 5mm x 4mm was made at the corneoscleral limbus. The anterior chamber was entered with a 23-gauge needle in a track anterior and parallel to the iris plane. The tube was trimmed such that 2 mm of the tube with the bevelled edge facing the endothelium was inserted into the anterior chamber and it was sutured with 9-0 nylon sutures to the sclera. Subsequently, the partial-thickness scleral flap was sutured to the sclera with 10-0 nylon sutures. The conjunctiva was sutured to the limbus at the end of the procedure.
Subsequently, a standard ECCE with heparin surface modified (HSM) PCIOL implantation was performed with a clear corneal incision in the superonasal quadrant extending from the 11'o clock to the 2'o clock position avoiding the area of the AGV implantation.
After surgery, all patients received topical antibiotic corticosteroid drops. Systemic prednisolone was tapered gradually. Antiglaucoma medications were removed or added as the IOP and the clinical status allowed. Success was defined as a Goldmann's applanation IOP less than or equal to 22 mmHg with no additional glaucoma surgeries or any other visually devastating postoperative complications at 3 months.
The statistical analysis included the paired 't' test and Pearson's chi-square test as indicated. The data was presented as mean ± standard deviation unless otherwise noted.
The average age of the patients was 60.67 ± 12.48 years (range 43 - 83 years). There were 11 female patients. The duration of the phacomorphic attack varied from 7 to 15 days (average of 12.41 ± 1.95 days) prior to presentation. All patients received topical and systemic antiglaucoma medications, topical beta-blockers (0.5% Timolol maleate twice daily), systemic acetazolamide and glycerol, along with systemic and topical corticosteroids in an attempt to decrease the IOP and inflammation.
The average preoperative IOP 3 days after presentation was 28 ± 5.01 mm Hg with 2.733 ± 0.961 antiglaucoma medications. In 6 eyes the IOP was less than 22 mm Hg with medications. All patients had a preoperative visual acuity of light perception and accurate projections of rays. Gonioscopy of the affected eyes had nearly 360° peripheral anterior synechiae while all the fellow eyes had deep anterior chambers and open angles. The average anterior chamber depth in the affected eye was 1.23 ± 0.08 mm versus 3.12 ± 0.46 mm in the fellow eye (P<0.001). The average lens thickness in the affected eye was 4.78 ± 0.62 mm versus 3.66 ± 0.84 mm in the fellow eye (P<0.01).
The follow-up of the patients ranged from 6 to 46 months with an average of 22.13 ± 12.05 months. The average IOP in the first postoperative week was 12 ± 1.69 mm Hg. without any medication, a significant improvement on the preoperative IOP (P<0.0001). The improvement in IOP persisted at 3 months (13.33 ± 2.79 mmHg; P<0.0001), 6 months (15.08 ± 2.9 mmHg; P<0.0001), 12 months (17.43 ± 3.59 mmHg; P<0.01) and 24 months (18.24 ± 2.17 mmHg; P<0.01) with respect to the preoperative IOP. The difference between the IOP in the first week and at 3 months after surgery was also significant (P<0.01), marked by a slight increase of about 1.33 mmHg at 3 months. The average IOP however remained within the desired range [Table - 1]. The change in the average IOP at 3 and 6 months was in the range of about 1.7 mmHg. This was however, not statistically significant (P=0.1390). Subsequent differences in the IOP at other intervals of follow-up was not significant [Table - 1]. Postoperative medications were not needed in the first 3 months following surgery. The average number of postoperative topical antiglaucoma medications used were 0.25 ± 0.152 at one year. Systemic antiglaucoma medication was not needed. No patient subsequently required any other glaucoma procedure for IOP control.
The average postoperative visual acuity in decimal notation of Snellen fraction was 0.278 ± 0.16 at 3 months. This corresponded to an approximate visual acuity of 6/24. YAG capsulotomy was performed in 4 patients with significant posterior capsular opacification. Three patients who had phacomorphic glaucoma for 7 days improved to 6/12 or more. All these 3 patients also had a preoperative IOP less than 22 mmHg. with medical therapy prior to surgery. This number was too small for statistical analysis. However, clinically we observed that the chances of visual rehabilitation are probably better in patients with better IOP control prior to surgery and shorter duration of phacomorphic glaucoma. In other patients, with a longer duration of symptoms, the intraocular inflammation was greater, causing vitreous haze, corneal oedema and IOL deposits. These patients did not regain good vision. Glaucomatous optic nerve head cupping of 0.6 or more was seen in all these 12 patients while the cupping was 0.3 to 0.5 in the 3 patients who regained visual acuity of 6/12 or more.
Four patients had complications, but IOP was controlled in all of them. Two patients developed an exudative membrane in the immediate postoperative period; this resolved with medical treatment and subsequent YAG capsulotomy. One patient had tube cornea touch for which the tube was readjusted on the fourth postoperative day. One patient developed a Tenon's cyst and the IOP was 22 mmHg in the first week following surgery. The IOP reduced to 14 mmHg after needling of the bleb at 2 weeks, without any additional antiglaucoma medications. Despite HSM PCIOL implantation, significant IOL deposits and fibrinous material were seen in 9 patients.
Phacomorphic glaucoma is peculiar to developing countries. The mechanism is perhaps related to an inherent tendency of the cataractous lens to undergo rapid hydration as it matures. This hydration is usually rapid with a sudden forward displacement of the iris lens diaphragm causing an approximation of the peripheral iris to the cornea and rapid development of irreversible synaechial closure. This causes pupillary block. The problem is compounded by a low medical awareness, and limited resources.
Cataract extraction alone may not ameliorate the condition. Inadequate control of IOP despite maximal antiglaucoma medication and presence of symptoms for more than 7 days are considered indications for a combined glaucoma and cataract surgery in this condition. Visual gain is also reported as superior with combined surgery.
ECCE with trabeculectomy is the standard procedure for combined extraction. This carries moderately good success rates. Simultaneous use of antimetabolites and use of various modifications of small incision cataract surgery (SICS) has further improved the outcome. SICS is neither feasible nor desirable in patients with phacomorphic glaucoma of more than 7 days' duration who develop extensive uveitis and synechiae. Although cataract extraction and PCIOL implantation yields good visual results in phacomorphic glaucoma, a combined glaucoma and cataract surgery results in superior IOP control. Routine filtration surgery is likely to fail in some forms of glaucoma including post-uveitic glaucoma.
Since the introduction of the first seton in 1912, many aqueous shunts have been used including the Molteno implant, the Schocket implant, the Krupin-Denver valve, [23,24] the Baerveldt implant and the Ahmed Glaucoma valve implant. These implants are designed to drain aqueous humor from the anterior chamber through a tube into a bulla overlying the plate or band implant that is located at the equatorial subconjunctival space. The AGV implant directs aqueous flow through the silicone tube and between two thin silicone elastomer membranes in a tapered chamber. It has a one-way valve mechanism that maintains an IOP at 8 mm Hg or higher. These implants result in better control of IOP in conditions where filtration surgery may fail.
In this study we observed that the visual outcome was better in patients with a shorter duration of phacomorphic glaucoma and good preoperative IOP control. HSM PCIOLs are considered to be extremely biocompatible and it is recommended that they be used in all eyes with active inflammation. However, we observed significant IOL deposits in our patients with time, and combined with the persistent vitritis, posterior capsular opacification and glaucomatous optic nerve head damage contributed t o suboptimal visual improvement. The visual outcome in our patients was comparable to that reported in other studies.
The decrease in post-surgical IOP was maximum in the first 3 months and showed a positive correlation with the measure of the preoperative IOP. We did not experience any hypertensive phase of the IOP related to the use of AGVs as has been reported by some authors. The complications were transient and did not compromise the IOP control. The probable advantages over conventional filtering surgery include the formation of excellent blebs and a persistent and steady control of IOP with minimal antiglaucoma medication over a 6-46 month follow-up period.
In our study, IOP control was maintained with surgery with minimal requirement of postoperative antiglaucoma medications. Visual acuity gains were better in patients with a shorter duration of the phacomorphic attack and better IOP control prior to surgery. Exudative membranes, posterior capsular opacification, vitritis, IOL deposits and optic nerve head changes were probable causes of poor visual restoration in many patients.
In conclusion, we would like to reiterate that though the procedure described is probably an expensive alternative to combined glaucoma filtering and cataract surgery, the steady IOP control maintained over time by this procedure suggests that it be performed more often to optimize visual gains in similar conditions. A randomized prospective clinical trial would help compare the two procedures and arrive at definite guidelines.
Source of Support:
Conflict of Interest:
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