Cataract surgery has the potential to contribute to the progression of preexisting corneal diseases; similarly, corneal disease can limit surgical techniques and even prevent well tolerated cataract extraction. Ensuring optimal visual outcomes requires the identification of preoperative corneal disease and risk factors for postoperative corneal complications. Management may include perioperative use of pharmacotherapy or alternative surgical techniques, and in cases of more severe corneal disease, may include simultaneous or staged keratoplasty. This review addresses commonly encountered epithelial, stromal and endothelial corneal diseases and offers guidance on perioperative management.
CORNEAL EPITHELIAL DISEASE
Corneal epithelial and ocular surface disease can complicate and be exacerbated by cataract surgery. Epithelial disease can range from local inflammatory or dry eye disease to infectious disease and even systemic inflammatory conditions. Good surgical outcomes require recognition of disease as well as adequate perioperative management and surgical planning to prevent undesired and potentially devastating complications.
Ocular surface disease
Cataract surgery is known to exacerbate ocular surface and dry eye disease , which can increase risk of corneal infection and melt . Patients with ocular surface disease can be managed with aggressive perioperative lubrication in mild disease and with topical steroids or cyclosporine in more advanced cases . A randomized prospective study demonstrated improved visual outcomes after multifocal lens implantation in patients treated with topical cyclosporine 0.05% , supporting its role in perioperative ocular surface health and visual outcomes. If evaporative tear loss impairs the intraoperative view, hydroxypropyl methylcellulose 2% gel may be used instead of balanced salt solution to decrease the frequency of irrigation needed during phacoemulsification . Minimizing postoperative eye drops may also help because of the known toxic effect of preservatives and medications such as nonsteroidal anti-inflammatory drugs.
Greater care must be exercised in the timing and surgical planning of patients with more severe, inflammatory ocular surface disease. Although aggressive lubrication can be sufficient to prevent complications in some conditions such as well controlled graft-versus-host disease , there is a risk of reactivation of disease and corneal melt in conditions like ocular cicatricial pemphigoid, Stevens–Johnsons syndrome and peripheral ulcerative keratitis [6–11]. Ensuring the disease is well controlled and quiet prior to operating may require systemic immunosuppressive therapy to avoid serious complications [6–11]. Furthermore, careful planning of the wound location may help to avoid triggering an exacerbation of disease. For example, smaller, clear corneal incisions likely decrease the inflammatory response to surgery in patients with cicatrizing conjunctivitis [7,9]. In other situations like Mooren's ulcer, scleral tunnel wounds or even extracapsular cataract extraction may help to avoid triggering corneal melt . Cataract surgery does not need to be avoided in such patients, but cautious surgical planning and disease control is imperative to a successful outcome.
Herpes simplex keratitis
Patients with a history of epithelial or stromal herpetic keratitis also require specific perioperative care. Although rare, recurrences of herpes simplex virus (HSV) keratitis have been reported following cataract surgery . Both prospective and retrospective data support the use of prophylactic antivirals in penetrating keratoplasty to reduce recurrence and graft rejection [13,14]. However, no studies have examined the role of antivirals in preventing HSV recurrence after cataract surgery. Although the triggers for HSV reactivation are still being studied, proposed reasons for recurrence after cataract surgery include surgical trauma and use of topical steroids . There are currently no guidelines for the dosing and duration of prophylactic antivirals, but the relatively benign side-effect profile makes administration reasonable in patients with a known history of herpetic keratitis. Nonsteroidal anti-inflammatory drugs may also be substituted for steroids in an effort to minimize reactivation risk . The preoperative evaluation should include assessment of history and clinical findings associated with HSV keratitis in order to initiate timely antiviral medications to prevent discomfort and further vision loss secondary to viral reactivation and secondary keratitis.
CORNEAL STROMAL DISEASE
Corneal stromal disease, including corneal dystrophies and scarring due to prior trauma, infection or inflammation, can significantly compromise visualization during cataract surgery. The resulting view can impair the surgeon's ability to perform critical steps, including continuous curvilinear capsulorhexis (CCC) and safe nuclear removal. The surgical approach can be modified to improve the view with techniques that range from capsular staining to alternative methods of illumination. Patients with visually significant corneal disease may require simultaneous partial or full thickness corneal transplantation, both for safe visualization during cataract extraction and for successful visual rehabilitation.
Capsular staining is a simple and commonly employed adjunct with cataract surgery. A report from the American Academy of Ophthalmology determined that both trypan blue 0.1% and indocyanine green 0.125–0.5% were effective in staining the anterior lens capsule to assist with capsulorhexis in routine cataract surgery. However, there are limited data for safety with posterior segment or prolonged anterior segment exposure; there may also be carcinogenic and mutagenic properties . More recent studies have evaluated staining quality and endothelial cell toxicity of alternative vital dyes [16,17▪▪], including patent blue, which has been approved as an alternative to trypan blue in Europe [17▪▪].
Corneal stromal opacification can induce backscatter and reflections from standard coaxial lighting that may further interfere with visualization. In these settings, alternative illumination techniques have been described to enhance the surgeon's intraoperative view and increase surgical safety. Use of an endoillumination probe either outside the eye or placed through a corneal paracentesis can be used in eyes with severe opacities to assist with CCC and nuclear removal . More recently, transconjunctival chandelier illumination has been described to allow visualization in cataract surgery with bullous keratopathy  as well as for endothelial keratoplasty [20,21]. This technique is hands-free and allows the surgeon to operate bimanually.
Cataract surgery and keratoplasty for stromal disease
Both corneal transplantation and cataract surgery should be considered when corneal disease is likely to limit visual improvement after cataract surgery or when the visibility for cataract surgery is markedly diminished. In these cases, staged penetrating keratoplasty (PKP) followed by cataract extraction or simultaneous surgery (triple procedure) can be performed. Staged procedures prolong the time for visual rehabilitation, and phacoemulsification after PKP may result in endothelial cell loss . However, the traditional triple procedure, consisting of PKP combined with cataract surgery, limits the surgical technique for cataract extraction and predictable correction of refractive errors including astigmatism after PKP.
Several approaches have been described to facilitate creation of a CCC and perform phacoemulsification during a triple procedure. Caporossi et al. described using a spatula to exert downward pressure on the lens to counter posterior pressure in order to facilitate CCC. Others have described using a temporary corneal graft from tissue not otherwise suitable for transplantation  or a temporary keratoprosthesis  to maintain a closed chamber and allow routine CCC and phacoemulsification prior to suturing the corneal graft in place. Alternatively, in patients with anterior-to-mid stromal disease, an anterior lamellar dissection can improve visibility for closed chamber phacoemulsification followed by removal of the residual corneal stroma and completion of penetrating keratoplasty [26–28]. Bayakara et al. described a technique whereby the phacoemulsification incision was placed through the stromal bed after a lamellar dissection, thus avoiding the need to place an additional incision or to decenter the graft to allow adequate space for a corneal incision.
Another modification described for patients with a healthy corneal endothelium involves performing anterior lamellar keratoplasty (ALK) in combination with phacoemulsification. Senoo  described a series of patients with cataracts and corneal opacification who underwent ALK (approximately two-third thickness) followed by phacoemulsification and suturing of the donor graft. Visual outcomes were good with a significantly decreased rate of postoperative endothelial cell loss as compared with PKP. A similar approach has been described incorporating the femtosecond laser to cut the host and donor cornea .
With the rising popularity of Descemet's-baring deep anterior lamellar keratoplasty (DALK), dissection to Descemet's membrane followed by phacoemulsification and grafting has been described [31,32▪▪]. Panda et al.[32▪▪] described a series of 20 patients undergoing this modified ‘triple’ with 18 of 20 patients having at least 20/60 vision postoperatively. This technique includes use of eccentric trephination, high-viscosity ophthalmic viscosurgical device over Descemet's membrane during phacoemulsification, and low vacuum and flow rates to minimize trauma to Descemet's membrane during cataract extraction. Given the enhanced wound stability and decreased rejection inherent in DALK, this approach should be considered in patients with a healthy corneal endothelium.
CORNEAL ENDOTHELIAL DISEASE
Given the predictable loss of endothelial cells following cataract surgery, careful consideration and planning is necessary when treating a patient with a compromised endothelium. The most commonly encountered endothelial disease is Fuchs’ corneal dystrophy, but low endothelial cell density (ECD) may also be present in patients with a history of corneal and intraocular inflammation or trauma . A modified surgical approach may limit damage to a compromised endothelium while some patients may benefit from simultaneous or staged keratoplasty.
Risk factors for endothelial cell loss
Although low preoperative ECD may not predispose patients to a greater percentage of endothelial cell loss , these patients have less endothelial cell reserve and therefore are more likely to be affected by any damage sustained during surgery. A retrospective study by Afshari et al. reviewed 30 years of PKP for Fuchs’ corneal dystrophy highlighting the role of cataract surgery in accelerating the progression of corneal decompensation in these patients. Seventeen patients were identified who underwent bilateral PKP for Fuchs’ after unilateral cataract extraction, a majority of whom (76%) required PKP in the pseudophakic eye first. The mean time to PKP in the pseudophakic eye was 2.2 years, and PKP was performed 3.2 years earlier than in the fellow eye. Furthermore, among 170 patients who underwent unilateral cataract surgery with subsequent unilateral PKP, 89.4% required the PKP in the pseudophakic eye. Therefore, cataract surgery can hasten the need for corneal surgery in patients with a compromised endothelium.
Additional factors may also place patients at risk for increased endothelial damage during surgery. Longer phacoemulsification time and shorter axial length have been shown to be risk factors for ECD loss . A recent retrospective analysis of cataract surgery performed in patients with low ECD (<1000 cells/mm2) supported short axial length as a risk for increased ECD loss, and posterior capsular rupture was associated with postoperative bullous keratopathy . Interestingly, metabolic stress from systemic diseases, such as diabetes mellitus, may also play a role in endothelial cell loss following intraocular surgery [36–39]. A recent prospective study demonstrated that endothelial cell loss 3 months after phacoemulsification was greater in diabetics than nondiabetics (6.2 versus 1.4%) . Similar differences have been seen between diabetic and nondiabetic patients following manual small incision cataract surgery . Preoperative identification of patients at risk for postoperative corneal decompensation is a necessary part of surgical planning.
Numerous studies have assessed and confirmed the role of ocular viscosurgical devices in endothelial protection during phacoemulsification. A soft-shell technique, first described by Arshinoff , combines dispersive and cohesive viscoelastics to cushion the endothelium. This approach has since been shown to afford superior endothelial protection compared with Healon (Abbott Medical Optics Inc., Santa Ana, CA, USA) as evidenced by decreased ECD loss  and decreased postoperative corneal pachymetry .
The impact of surgical technique for nuclear removal on ECD loss is less clear, and most studies do not suggest a preferred technique. Though a phaco-chop technique uses less ultrasound energy than other approaches, recent studies have not shown a difference in ECD loss as compared to stop-and-chop  or divide-and-conquer . Interestingly, studies comparing both conventional extracapsular cataract extraction (ECCE)  and manual small incision extracapsular cataract surgery  to phacoemulsification also showed no difference in ECD loss between the two techniques. Furthermore, patients with dense cataracts may suffer greater ECD loss from phacoemulsification as compared with ECCE ; therefore, ECCE should be considered in patients in whom phacoemulsification is predicted to result in high ultrasound use.
Cataract surgery and keratoplasty for endothelial disease
In light of the inherent endothelial damage during cataract surgery, staged versus simultaneous cataract surgery and keratoplasty, particularly Descemet's stripping endothelial keratoplasty (DSEK), should be considered in patients whom are at risk for postoperative corneal edema. However, it is difficult to predict the timing of corneal decompensation in patients with a compromised endothelium, and therefore guidelines for these patients are in flux. Seitzman et al. reviewed 136 eyes with Fuchs’ corneal dystrophy which underwent cataract surgery and suggested that eyes with preoperative pachymetry of greater than 640 μm may be better suited for simultaneous surgery. This recommendation has since been adopted by the American Academy of Ophthalmology's Preferred Practice Pattern . With appropriate modifications to surgical technique, Terry et al. showed no difference in postoperative ECD with a staged or joint DSEK and cataract surgery, attesting to the safety of performing simultaneous surgery on graft survival.
Both PKP and DSEK have also been shown to accelerate cataract formation [50–53]; thus, some patients with minimal lenticular changes may be better suited for simultaneous keratoplasty and lens extraction instead of keratoplasty alone. Age greater than 50 has previously been shown to be a risk factor for rapid cataract development after PKP [50,51]. A recent study showed a similar outcome in phakic patients following DSEK, with the likelihood of requiring cataract surgery within 3 years of DSEK increasing from 7% in those 50 years or younger to 55% in those over 50 years of age . This may be useful when counseling patients and designing a surgical plan in eyes with little to no cataract and visually significant endothelial disease.
Cataract surgery can be challenging in patients with preexisting corneal disease. Proper preoperative assessment of corneal disease can aid in optimal treatment, surgical planning and visual outcomes. Evolution of cataract surgical technique and enhancement in technology may further assist in managing these complicated patients.
Conflicts of interest
The authors do not report any conflict of interest.
REFERENCES AND RECOMMENDED READING
Papers of particular interest, published within the annual period of review, have been highlighted as:
- ▪ of special interest
- ▪▪ of outstanding interest
Additional references related to this topic can also be found in the Current World Literature section in this issue (pp. 79–80).
1. Cho YK, Kim MS. Dry eye after cataract surgery
and associated intraoperative risk factors. Korean J Ophthalmol 2009; 23:65–73.
2. Movahedan A, Djalilian AR. Cataract surgery
in the face of ocular surface disease. Curr Opin Ophthalmol 2012; 23:68–72.
3. Donnenfeld ED, Solomon R, Roberts CW, et al. Cyclosporine 0.05% to improve visual outcomes after multifocal intraocular lens implantation. J Cataract Refract Surg 2010; 36:1095–1100.
4. Chen YA, Hirnschall N, Findl O. Comparison of corneal wetting properties of viscous eye lubricant and balanced salt solution to maintain optical clarity during cataract surgery
. J Cataract Refract Surg 2011; 37:1806–1808.
5. Penn EA, Soong HK. Cataract surgery
in allogeneic bone marrow transplant recipients with graft-versus-host disease. J Cataract Refract Surg 2002; 28:417–420.
6. Sainz de la Maza M, Tauber J, Foster CS. Cataract surgery
in ocular cicatricial pemphigoid. Ophthalmology 1988; 95:481–486.
7. Elkins BS, Clinch TE. Clear corneal cataract surgery
in ocular cicatricial pemphigoid. J Cataract Refract Surg 1997; 23:132–133.
8. Geerling G, Dart JKG. Management and outcome of cataract surgery
in ocular cicatricial pemphigoid. Graefe's Arch Clin Exp Ophthalmol 2000; 238:112–118.
9. Sangwan VS, Burman S. Cataract surgery
in Stevens–Johnson syndrome. J Cataract Refract Surg 2005; 31:860–862.
10. Perez VL, Azar DT, Foster CS. Sterile corneal melting and necrotizing scleritis after cataract surgery
in patients with rheumatoid arthritis and collagen vascular disease. Semin Ophthalmol 2002; 17:124–130.
11. Sangwan VS, Surender P, Burman S. Cataract surgery
in patients with Mooren's ulcer. J Cataract Refract Surg 2005; 31:359–362.
12. Barequet IS, Wasserzug Y. Herpes simplex keratitis after cataract surgery
. Cornea 2007; 26:615–617.
13. Barney NP, Foster CS. A prospective randomized trial of oral acyclovir after penetrating keratoplasty for herpes simplex keratitis. Cornea 1994; 13:232–236.
14. Garcia DD, Farjo Q, Musch DC, Sugar A. Effect of prophylactic oral acyclovir after penetrating keratoplasty for herpes simplex keratitis. Cornea 2007; 26:930–934.
15. Jacobs DS, Cox TA, Wagoner MD, et al. Capsule staining as an adjunct to cataract surgery
; a report from the American Academy of Ophthalmology (Ophthalmic Technology Assessment). Ophthalmology 2006; 113:707–713.
16. Rodrigues EB, Penha FM, de Paula Fiod Costa E, et al. Ability of new vital dyes to stain intraocular membranes and tissues in ocular surgery. Am J Ophthalmol 2010; 149:265–277.
17▪▪. Thaler S, Hofmann J, Bartz-Schmidt K, et al. Methyl blue and aniline blue versus patent blue and trypan blue as vital dyes in cataract surgery
: capsule staining properties and cytotoxicity to human cultured corneal endothelial cells. J Cataract Refract Surg 2011; 37:1147–1153.
Although the known endothelial toxicity of trypan blue may not be clinically significant, this article evaluated the toxicity and capsular staining of multiple alternative dyes. Patent blue, already approved for capsular staining in Europe, showed no endothelial toxicity as compared to trypan blue with adequate capsular staining.
18. Nishimura A, Kobayashi A, Segawa Y, Sugiyama K. Endoillumination-assisted cataract surgery
in a patient with corneal opacity. J Cataract Refract Surg 2003; 29:2277–2280.
19. Oshima Y, Shima C, Maeda N, Tano Y. Chandelier retroillumination-assisted torsional oscillation for cataract surgery
in patients with severe corneal opacity. J Cataract Refract Surg 2007; 33:2018–2022.
20. Inoue T, Oshima Y, Shima C, et al. Chandelier illumination to complete Descemet stripping through severe hazy cornea during Descemet-stripping automated endothelial keratoplasty. J Cataract Refract Surg 2008; 34:892–896.
21. Inoue T, Oshima Y, Hori Y, et al. Chandelier illumination for use during descemet stripping automated endothelial keratoplasty in patients with advanced bullous keratopathy. Cornea 2011; 30 (Suppl 1):S50–S53.
22. Nagra PK, Rapuano CJ, Laibson PL, et al. Cataract extraction following penetrating keratoplasty. Cornea 2004; 23:377–379.
23. Caporossi A, Traversi C, Simi C, Tosi GM. Closed-system and open-sky capsulorhexis for combined cataract extraction and corneal transplantation. J Cataract Refract Surg 2001; 27:990–993.
24. Nardi M, Giudice V, Marabotti A, et al. Temporary graft for closed-system cataract surgery
during corneal triple procedures. J Cataract Refract Surg 2001; 27:1172–1175.
25. Menapace R, Skorpik C, Grasl M. Modified triple procedure using a temporary keratoprosthesis for closed-system, small-incision cataract surgery
. J Cataract Refract Surg 1990; 16:230–234.
26. Malbran ES, Malbran E, Buonsanti J, Adroque E. Closed-system phacoemulsification and posterior chamber implant combined with penetrating keratoplasty. Ophthalmic Surg 1993; 24:403–406.
27. Ardjomand N, Fellner P, Moray M, et al. Lamellar corneal dissection for visualization of the anterior chamber before triple procedure. Eye 2007; 21:1151–1154.
28. Baykara M, Ucan G. Modifying the position of cataract incisions in triple procedure. Eur J Ophthalmol 2008; 18:891–894.
29. Senoo T. Combined surgery with deep lamellar keratoplasty. Semin Ophthalmol 2001; 16:126–136.
30. Lee D, Kim J-H, Oh S-H, et al. Femtosecond laser lamellar keratoplasty to aid visualization for cataract surgery
. J Refract Surg 2009; 25:902–904.
31. Muraine MC, Collet A, Brasseur G. Deep lamellar keratoplasty combined with cataract surgery
. Arch Ophthalmol 2002; 120:812–815.
32▪▪. Panda A, Sethi HS, Jain M, et al. Deep anterior lamellar keratoplasty with phacoemulsification. J Cataract Refract Surg 2011; 37:122–126.
DALK is being performed more frequently. This article reviews a series of patients undergoing simultaneous DALK and phacoemulsification and demonstrates promising visual outcomes while describing an appropriate and well tolerated surgical technique for performing phacoemulsification following baring of Descemet's membrane.
33. Hayashi K, Yoshida M, Manabe S, Hirata A. Cataract surgery
in eyes with low corneal endothelial cell density. J Cataract Refract Surg 2011; 37:1419–1425.
34. Afshari NA, Pittard AB, Siddiqui A, et al. Clinical study of Fuchs corneal endothelial dystrophy leading to penetrating keratoplasty: a 30 year experience. Arch Ophthalmol 2006; 124:777–780.
35. Walkow T, Anders N, Klebe S. Endothelial cell loss after phacoemulsification: relation to preoperative and intraoperative parameters. J Cataract Refract Surg 2000; 26:727–732.
36. Yamazoe K, Yamaguchi T, Hotta K, et al. Outcomes of cataract surgery
in eyes with a low corneal endothelial cell density. J Cataract Refract Surg 2011; 37:2130–2136.
37. Hugod M, Storr-Paulsen A, Norregaard J, et al. Corneal endothelial cell changes associated with cataract surgery
in patients with type 2 diabetes mellitus. Cornea 2011; 30:749–753.
38. Mathew P, David S, Thomas N. Endothelial cell loss and central corneal thickness in patients with and without diabetes after manual small incision cataract surgery
. Cornea 2011; 30:424–428.
39. Rosado-Adames N, Afshari NA. The changing fate of the corneal endothelium in cataract surgery
. Curr Opin Ophthalmol 2012; 23:3–6.
40. Arshinoff SA. Dispersive-cohesive viscoelastic soft-shell technique. J Cataract Refract Surg 1999; 25:167–173.
41. Miyata K, Nagamoto T, Maruoka S, et al. Efficacy and safety of the soft-shell technique in cases with a hard lens nucleus. J Cataract Refract Surg 2002; 28:1546–1550.
42. Tarnawska D, Wylegata E. Effectiveness of the soft-shell technique in patients with Fuchs’ endothelial dystrophy. J Cataract Refract Surg 2007; 33:1907–1912.
43. Park J, Lee SM, Kwon JW, et al. Ultrasound energy in phacoemulsification: a comparative analysis of phaco-chop and stop-and-chop techniques according to the degree of nuclear density. Ophthal Surg Lasers Imag 2010; 41:236–241.
44. Storr-Paulsen A, Norregaard JC, Ahmed S, et al. Endothelial cell damage after cataract surgery
: divide-and-conquer versus phaco-chop technique. J Cataract Refract Surg 2008; 34:996–1000.
45. Bourne R, Minassian D, Dart J. Effect of cataract surgery
on the corneal endothelium, modern phacoemulsification compared with extracapsular cataract surgery
. Ophthalmology 2004; 111:679–685.
46. Gogate P, Ambardekar P, Kulkarni S, et al. Comparison of endothelial cell loss after cataract surgery
: phacoemulsification versus manual small-incision cataract surgery
: six-week results of a randomized control trial. J Cataract Refract Surg 2010; 36:247–253.
47. Seitzman G, Gottsch J, Stark W. Cataract surgery
in patients with Fuchs’ corneal dystrophy expanding recommendations for cataract surgery
without simultaneous keratoplasty. Ophthalmology 2005; 112:441–446.
48. American Academy of Ophthalmology Cataract and Anterior Segment PPP Panel. Cataract in the Adult Eye Preferred Practice Patterns. San Francisco, CA: AAO October 2011. http://www.aao.org/ppp
49. Terry MA, Shamie N, Chen ES, et al. Endothelial keratoplasty for Fuchs’ dystrophy with cataract: complications and clinical results with the new triple procedure. Ophthalmology 2009; 116:631–639.
50. Payant JA, Gordon LW, VanderZwaag R, et al. Cataract formation following corneal transplantation in eyes with Fuchs’ endothelial dystrophy. Cornea 1990; 9:286–289.
51. Martin TP, Reed JW, Legault C, et al. Cataract formation and cataract extraction after penetrating keratoplasty. Ophthalmology 1994; 101:113–119.
52. Price MO, Price DA, Fairchild KM, Price FW. Rate and risk factors for cataract formation and extraction after Descemet stripping endothelial keratoplasty. Br J Ophthalmol 2010; 94:1468–1471.
53. Tsui JYM, Goins KM, Sutphin JE, Wagoner MD. Phakic Descemet stripping automated endothelial keratoplasty: prevalence and prognostic impact of postoperative cataracts. Cornea 2011; 30:291–295.