Corneal opacity resulting from microbial keratitis is a leading cause of ocular morbidity in developing country.1–4 It is frequently associated with cataract, particularly in elderly patients.5 Over past few years, we have observed a considerable number of one-eyed patients (persons with no vision in one eye due to various causes such as trauma, optic neuropathy, and retinal disorders) undergoing triple procedure for cataract with corneal opacity (CCO). Although triple procedure, a surgical technique that involves both cataract surgery and penetrating keratoplasty (PK) simultaneously, is considered standard of care for CCO, it carries a potential risk of intraoperative and postoperative complications that may cause permanent vision loss for the one-eyed patients.6,7 Furthermore, treatment outcome of this procedure depends heavily on other factors such as compliance of patient and availability of good-quality donor cornea, which are often unsatisfactory in underprivileged states. Taken together, these issues become a major concern for the one-eyed patients who need early ambulatory vision sufficient to carry out daily routine activities.
Cataract surgery alone has been reported to provide adequate ambulatory vision for patients with CCO.8–12 However, no study has analyzed the outcome of cataract surgery alone as an alternative therapeutic option for the one-eyed patients. In this study, we sought to determine whether cataract surgery alone may be used as an alternative to triple procedure for one-eyed patient with CCO. Therefore, this study first assessed the visual outcome and safety of cataract surgery alone, and then compared its long-term visual outcome with the triple procedure in the one-eyed patient.
In this retrospective matched case-control study, medical records of 55 one-eyed patients who underwent cataract surgery with or without PK for the indication of CCO from January 2015 to June 2018 were retrospectively reviewed. The study was approved by institutional ethics committee. One-eyed patients with CCO were defined as patients with both cataract (grade ≥2) and corneal opacity involving the visual axis limiting best corrected visual acuity (BCVA) to <20/200 and no expectancy of visual improvement in the other eye. Only eyes with partially visible lens and pupillary margin on dilatation by slit-lamp examination were included. The exclusion criteria were eyes with dense corneal opacity completely masking the anterior segment visibility and with minimal corneal opacity (nebular) with significant cataract (n = 4), eyes with diseases adversely affecting the visual outcome such as preexisting uveitis (n = 1), retinal abnormalities (n = 3), and advanced uncontrolled glaucoma (n = 1). 2 patients who lost to follow-up were also excluded. Finally, a total of 44 one-eyed patients with CCO were analyzed. Based on the surgery performed in this study, the patients were divided into two groups: group A consisting of 25 patients treated by cataract surgery alone, and group B including 19 matched patients who were managed by triple procedure. Matching was performed for age (±10 years), preoperative vision (<20/200), degree of corneal opacity, and grading of cataract. Location and depth of corneal opacity were assessed by slit-lamp using Agrawal13 classification as follows: (1) nebular: scars that involved superficial stroma allowing detailed visibility of iris, (2) macular: scars that involved half of stroma, obscuring iris details with visible pupillary margin, (3) leukoma: scars that involved more than half of stroma, obscuring iris and pupil details completely, and (4) adherent leukoma: leukomatous corneal scar that resulted from healing of perforated corneal ulcer (corneoiridic scar). Anterior segment optical coherence tomography (ASOCT) was performed for the selected cases (n = 19 eyes, 11 eyes in group A and 8 eyes in group B) in which depth could not be assessed or doubt about capsular adherence with opacity was realized on slit-lamp examination. Similarly, based on Lens Opacity Classification System III (LOCS III) through the best possible clear cornea, cataract grade (≥2) was taken as matching criteria in all cases.
Patient history and preoperative parameters, including microbial etiology for the corneal opacity, the type of cataract, uncorrected visual acuity (UCVA), and BCVA with logarithm of the minimum angle of resolution (LogMAR) notations were reviewed. A preoperative keratometry reading was noted for the same eye if keratometry was possible or a standard keratometry reading (43.5 diopters) was obtained. Intraocular pressure was measured by noncontact tonometry, and posterior segment evaluation was done with B-scan ultrasonography.
All patients were managed with cataract extraction and IOL implantation with or without simultaneous PK under peribulbar anesthesia. In group A, cataract surgery was performed by phacoemulsification or small incision cataract surgery (SICS) using various methods to enhance the detailed visualization of anterior segment.8–10,14–19 Standard corneal triple procedure with extracapsular cataract extraction and intraocular lens implantation was performed in group B. Additional maneuvers, including synechiolysis, pupillary sphincterotomy, optical iridectomy, iris hook application, and anterior vitrectomy were performed as and when required.
All patients received routine postoperative regimen of cataract surgery and triple procedure, including prophylactic systemic acyclovir in case of resolved stromal viral keratitis. A minimum of 3 years follow-up was recorded for analysis, including final visual acuity with spectacle or contact lens correction. In case of unavailability of refraction, final visual acuity with pinhole was considered for analysis.
The primary outcome measure was the improvement of visual acuity and secondary outcomes were consequences of procedure and period of maintained ambulatory vision. Functional success was defined as postoperative vision gain of ≥20/200 (ambulatory vision). Anatomical success was stated as no increase in preexisting corneal opacity in group A and maintenance of clear graft in group B. Period of maintained ambulatory vision was recorded for each eye. The BCVA ≥20/200 was considered ambulatory vision according to the definition of blindness by National Program for Control of Blindness (NPCB), India.20
Statistical analysis was performed using Epi Info 7 (CDC, Atlanta, GA). Frequencies of demographic and clinical variables were calculated for each group. The normality of all data samples was first checked by Shapiro-Wilk test. Categorical variables were compared using a Pearson χ2 test and Spearman correlation. Continuous variables were compared using a 2-tailed independent sample t test and Mann-Whitney U test. Nonparametric statistical tests were used for nonnormal distributed data. Kaplan-Meier survival analysis was performed to evaluate the duration of maintained ambulatory vision. P ≤ 0.05 was considered significant.
Table 1 presents the detailed clinical data of cases and controls. In both groups, the most common etiology of corneal opacity was fungal followed by bacterial and viral (herpes simplex virus, HSV) keratitis, and the commonest cause of permanent visual loss in other eye was phthisis bulbi. There was no significant difference in age, cataract grade, degree, and etiology of corneal opacities (P > 0.05) between group A (cataract surgery alone, n = 25) and group B (triple procedure, n = 19). Preoperatively, all patients had a BCVA <20/200. In group A, 11 patients underwent phacoemulsification [superior (n = 6) and temporal (n = 5) corneal wound], and 14 had SICS [superior (n = 9) and temporal (n = 5)]. Mean age at the time of operation was 61.2 ± 8.1 years and 62.5 ± 6.9 years in group A and B, respectively. In group B, average graft size was 7.5 ± 1.3 mm. All patients were followed for 37.52 ± 6.0 (range, 36–45) months. Most of the patients belonged to rural area (n = 38) and were uneducated.
At each follow-up, the mean postoperative BCVA was found significantly better than the preoperative vision in both groups (P < 0.01). At the end of 3 years of follow-up, mean BCVA of group A was significantly better than group B (P = 0.012) (Figs. 1 and 2).
Overall, in group A, postoperative vision improved in 20 (80%) patients, whereas the remaining 5 had insignificant or no improvement. Of these 5 patients, 1 had intraoperative Descemet membrane detachment (DMD), which was subsequently managed by intracameral gas injection (SF6), and one other showed recurrence of microbial keratitis while vision remained unchanged in 3 patients (Table 2). None of the patients in group A improved beyond 20/60 at the end of follow-up, whereas in group B, 11 patients (57%) had BCVA ≥20/60 [(2: 20/30), (4: 20/40), (5: 20/60)] at 1 year, which decreased to 9 patients (47%) at the end of 3 years (Fig. 3). Anatomically, 13 grafts (68%) remained clear and 6 grafts (37%) became hazy at final visit. Though all patients with triple procedure (group B) showed improvement in postoperative vision, 6 (37%) patients experienced deterioration of final visual acuity (at least three lines drop with Snellen) due to graft rejection (n = 2), graft infection (n = 2), endophthalmitis (n = 1), and traumatic graft dehiscence (n = 1) and 2 (11%) patients had vision drop of one line as a result of reversible graft rejection (Table 2; Figs. 4 and 5).
The persistence of corneal opacity was the commonest cause of limited visual outcome in group A accounting for all cases, whereas it was graft infection and graft rejection in group B. In group A, one case had DMD resulting in no improvement in postoperative vision and in one case of group B, IOL could not be implanted due to posterior capsular tear and positive vitreous pressure that necessitated automated anterior vitrectomy. Other patients had uneventful surgery in both groups.
The mean period of maintained ambulatory vision for eyes in group A was longer (33.36 ± 11.97 months) than that of eyes with triple procedure (26.5 ± 13.5 months) (Log-rank test, P = 0.245) (Fig. 6). Survival analysis in both groups revealed hazard ratio (HR) 0.67 [95% confidence interval (CI) 0.20–2.19], which implies that cataract surgery alone (group A) carried a less risk of losing ambulatory vision by 33%. Regardless of adverse consequences, ambulatory vision was present in 20 (80%) and 13 (68%) patients in groups A and B, respectively, at the end of follow-up. 5 patients (20%) in group A and 6 patients (32%) in group B, who failed to achieve the minimum vision (≥20/200), were advised for penetrating keratoplasty and regraft, respectively. The postoperative visual gain in 5 patients who had PK as second procedure improved significantly to 20/80 (n = 2) and 20/60 (n = 2) at the end of 1 year except one who developed graft infection of viral etiology at 4 months of follow-up, eventually leading to graft failure. At the end of 1 year, graft survival and mean BCVA of PK of group A were 80% and 0.84 ± 0.65, respectively, which was not significantly different from group B (graft survival 84% and mean BCVA 0.73 ± 0.59).
Preoperative factors predicting the prognosis of the cases were analyzed by regression model. In group A, the cumulative survival of ambulatory vision was insignificantly affected by post HSV corneal opacity (HR 4.47, P = 0.291) and by presence of deep vascularization (HR 1.976, P = 0.496), whereas it was adversely affected by nondilating pupil (HR = 9.5, P = 0.059) and leukomatous type of corneal opacity (HR = 4.87, P = 0.043). Visual outcome of group B was significantly affected by post HSV scar (HR = 7.91, P = 0.024) and by deep vascularization (HR = 3.49, P = 0.041) causing higher risk for graft failure.
In the developing countries where the demand of corneal transplantation is high due to the increased rate of corneal infection resulting in blindness, a large population remains underserved.21 The paucity of functional eye banks and good-quality donor tissue have been another important limiting factor prolonging the waiting period for corneal transplantation. These unresolved issues prompted the authors to choose cataract surgery alone as a temporizing method to manage CCO in one-eyed patients who were willing to have minimal vision, allowing them to perform routine activity during waiting period for PK.
Analyzing the outcomes of cataract surgery alone (group A), we found a significantly (P < 0.05) improved postoperative vision from the baseline to 0.76 ± 0.40 in more than two-third of our patients, enhancing their overall quality of life. Although the patients treated by triple procedure (group B) had better mean BCVA than group A during early postoperative period, no significant difference in mean postoperative visual gain between both groups was found at the end of 1 year (P = 0.262). Furthermore, throughout the follow-up period of 3 years, the mean BCVA of group A (0.76) remained significantly better than that of group B (0.94) who suffered serious or more adverse events resulting in graft failure.
Although there exist few studies evaluating the outcome of cataract surgery in the presence of corneal opacification,8–10,18 this is the first study that determines the visual outcome and safety of cataract surgery alone and compares its long-term visual outcome with triple procedure in one-eyed patients. Bhartiya et al8 and Titiyal et al10 evaluated the surgical outcome of trypan blue assisted phacoemulsification and SICS in 11 and 12 eyes with coexisting corneal opacity, respectively, and found suboptimal visual acuity in all of their patients. Panda et al11 performed phacoemulsification for 205 patients with extensive corneal opacities resulted mostly from healed keratitis and documented improved BCVA from 40/200 to 20/60 (5%) and 20/80 (68%) for all of their patients without experiencing any notable complications; they thus advocated phacoemulsification as a safe and feasible primary therapeutic option for those cases in which PK was not promising or possible. Our study yielded similar results with visual gain from <20/200 to 20/80 in 36% patients and 20/60 in 24% patients in group A and this postoperative vision, however, was sufficient to allow them to perform their daily life. None of the previous studies had revealed association between the severity of corneal opacity and the improvement in BCVA until Ho et al12 demonstrated suboptimal BCVA in presence of severe corneal opacity in his recent study. It can be presumed that these variations in outcome among different studies might have been resulted from lack of uniform parameters of opacity grading.
Performing a successful cataract surgery in the presence of corneal opacity has always been a challenging task due to poor visualization of intraocular morphology. Various surgical modifications, such as multiple sphincterotomy, iris hook application, use of dye, and endo-illuminators, have been used to enlarge the visible pupillary area, improving the success rate. We performed cataract surgery successfully for all of our patients by phacoemulsification or SICS using various techniques, which enhanced visualization of lenticular morphology through opaque corneas during the surgery (Fig. 4). The technique of cataract surgery was primarily based on the visibility and grading of cataract; hard cataract and dense corneal opacity were preferably managed by SICS to avoid further loss of corneal endothelial cells.22
Triple procedure is considered a standard therapeutic method for restoring vision in patients with CCO with varying graft survival rate ranging from 60% to 100%.23–28 In our series of 19 patients (group B), functional success in terms of visual gain and graft survival was found in 89.7% cases at 6 months, but it declined to 73.6% and 68.4% at second and third year, respectively. This trend is similar to that described by Sridhar et al27 who showed graft survival rates of 88.9%, 83.2%, and 76% at 12 months, 24 months, and 36 months, respectively. Both studies by Sridhar et al and ours showed poor graft-survival rate compared with the other reports.29,30 It is obvious from these studies that results of triple procedure are suboptimal if microbial keratitis forms the major indication of surgery.
Though the vision improved significantly at each follow-up in group A patients, the continuing presence of corneal opacity was a major problem that severely limited their visual function. 5 group A patients who subsequently underwent PK owing to poor vision achieved a satisfactory 1-year graft survival and postoperative BCVA similar to group B. Thus, sequential PK presumably offers greater safety and predictability in such patients. Although the triple procedure is considered a safe surgery with a reasonable visual recovery for CCO, graft rejection and infection are perhaps two serious complications after corneal transplantation, particularly in developing countries.26 Furthermore, this procedure always requires a regular follow-up visit to clinic with which these patients often fail to comply, thus adversely affecting the outcome. Because all of our patients were one-eyed, elderly, and dependent on their relatives for assistance, the regular follow-up posed a real problem for them. Additionally, being uneducated from rural background and from low socioeconomic status, they often tend to ignore their symptoms associated with complications of corneal transplantation leading to graft failure and subsequent vision loss. Concerns about safety and maintenance of ambulatory vision are another unique characteristics of these patients. Taking all these issues into consideration, management of CCO in such patients must focus primarily at providing long-term stable ambulatory vision so that they could perform their daily routine activities.
Several factors seem to predict which patient would gain optimal postoperative vision and therefore prompt the surgeon to elect the surgical options. These factors are etiology and type of opacity, presence of deep vascularization, and diameter of pupil. Our results suggest that outcome of cataract surgery alone is adversely affected by the presence of leukomatous opacity that results in poor visual gain and small pupillary diameter, which renders the surgery difficult leading to suboptimal visual gain. On the other hand, triple procedure seems to be adversely affected by presence of post HSV scar and deep vascularization, which makes the graft prone to infection and rejection followed by graft failure. Despite the fact that the patients who underwent cataract surgery alone had a greater incidence of recurrent keratitis from post HSV scar, their postoperative vision was insignificantly affected.
Several limitations of this study must be recognized. The major limitation was lack of objective criteria to assess corneal opacity. Additionally, the results of this study are not applicable to the patients with dense corneal opacity without any visibility of anterior chamber or the patients who have dense cataract with minimal opacity. Furthermore, the results of the present study cannot be generalized to other developed countries where the demographic profile of the patients, their lifestyle, and requirements may be entirely different.
In developing countries, considering the associated potential risks and paucity of good-quality donor cornea with triple procedure, cataract surgery with IOL implantation alone can be considered as an alternative or temporary option to provide stable ambulatory vision in one-eyed patients.
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