Seng-Ei Ti

Analysis of variation in success rates in conjunctival autografting for primary and recurrent pterygium

AIMS To evaluate the success rates of conjunctival autografting for primary and recurrent pterygium performed in a tertiary ophthalmic centre. METHODS The outcome of 139 cases with primary pterygia and 64 cases with recurrent pterygia who underwent excision with conjunctival autografting was retrospectively reviewed. Outcome was evaluated in terms of recurrence of pterygia onto the cornea. The recurrence rates were determined using Weibull survival functions, in a mixture model that included a component allowing for cure. The suitability of this model was verified using Turnbulls non-parametric method for interval censored data (1974). Estimated recurrence free probabilities were based on the fitted Weibull survival curves. RESULTS Mean follow up was 8.4 months in the primary group, and 9.5 months for the recurrent group. 29 out of 139 cases of primary pterygia recurred (20.8%) while 20 out of 64 cases in the recurrent group (31.2%) recurred. Recurrence rates varied widely among surgeons, ranging from 5% to 82%. Recurrence rates were inversely related to previous experience in performing conjunctival grafting. The recurrence free probability was 84% at 3 months, 73% at 1 year for primary pterygia, and 80% at 3 months, 67% at 1 year for recurrent pterygia. There was no statistical difference in recurrence rates between primary and recurrent groups (p= 0.80). CONCLUSION The success of conjunctival autografting for pterygium in this series varies widely, and may be related to a significant learning curve or differing surgical techniques for this procedure. This may account for the wide variation in reported success of this procedure in the ophthalmic literature.

Tectonic corneal lamellar grafting for severe scleral melting after pterygium surgery

PURPOSE To describe the technique and review the indications and success of tectonic corneal lamellar grafting for the management of severe scleral melts after pterygium surgery. DESIGN Retrospective, noncomparative, interventional case series. PARTICIPANTS Twenty cases of severe scleral necrosis after pterygium surgery (1993-1999). INTERVENTION Tectonic corneal lamellar grafting. Surgery involved (1) removal of all devitalized or infected scleral tissue surrounding the melt; (2) use of lamellar or full-thickness donor corneal tissue, fashioned to fit the scleral defect exactly or a 0.25-mm diameter larger; and (3) placement of a pedicled or free conjunctival flap over the corneal lamellar graft. MAIN OUTCOME MEASURES Eradication of progressive scleral necrosis, preservation of globe integrity, eradication of infection, and preoperative and postoperative visual acuity. RESULTS Sixteen (80%) of 20 cases developed severe scleral necrosis that required tectonic surgery after bare sclera pterygium excision with mitomycin C or beta-irradiation. Surgery was also therapeutic to eradicate progressive infection in 6 cases of infective scleritis that did not respond to maximal medical treatment. Scleral melting presented 1 month to 20 years after initial pterygium surgery in healthy, immune-competent adults. Therapeutic and tectonic success was achieved in 19 cases (95%); in 1 case, recurrence of fusarium fungal infection led to severe graft necrosis and intraocular spread. Among the cases of infectious scleritis, three eyes required repeat lamellar grafting to successfully eradicate infection. CONCLUSIONS Tectonic and therapeutic lamellar keratoplasty, combined with aggressive antibiotic therapy, preserved globe integrity and eradicated infection in cases of severe scleral melting after pterygium surgery.

Postoperative inflammation : Extracapsular cataract extraction versus phacoemulsification

PURPOSE To quantitatively compare postoperative inflammation after extracapsular cataract extraction (ECCE) with that after phacoemulsification in an Asian population. SETTING Singapore National Eye Center, Singapore. METHODS In this prospective, randomized, double-masked clinical trial, patients having cataract surgery were randomized to receive ECCE (n = 16) or phacoemulsification (n = 18). Diabetics were excluded. Two surgeons performed both types of surgery and implanted a 6.0 mm optic intraocular lens. Inflammation was assessed qualitatively by slitlamp grading of cells and flare and quantitatively using the Kowa flare meter. One independent postoperative investigator performed the slitlamp examination and laser flare meter readings. RESULTS The ECCE and phacoemulsification groups were comparable (P > .05) in age, sex, ethnicity, and preoperative flare levels. The combined slitlamp inflammatory scores (anterior chamber cells and flare) and mean laser flare meter readings showed the ECCE group had significantly higher mean flare measurements than the phacoemulsification group at days 4 (P = .0012), 8 (P = .0013), 15 (P = .0013), 30 (P = .0004), and 60 (P = .0164). Flare levels in the ECCE group returned to preoperative values by the second month; the phacoemulsification group achieved preoperative levels by 1 month. The clinical inflammatory assessment score correlated closely to the flare level readings. CONCLUSION Phacoemulsification induced less inflammation than ECCE, with the difference most marked in the first month after surgery.

Amniotic membrane transplantation in entropion surgery

PURPOSE To evaluate the role of amniotic membrane transplantation in the management of cicatricial eyelid entropion. DESIGN Prospective, noncomparative interventional case series. PARTICIPANTS Eighteen consecutive patients with cicatricial entropion. METHODS A gray line lid split procedure with vertical anterior lamella repositioning was performed on 25 eyelids (upper or lower) of 18 patients with moderate to severe cicatricial entropion. Preserved human amniotic membrane (AM) was used to cover the bare tarsus up to the lid margin and secured with running 7-0 Vicryl. Impression cytology of the AM was performed at various stages postoperatively to study the epithelialization process. MAIN OUTCOME MEASURES (1) Reepithelialization of bare tarsus, (2) extent of tarsal shrinkage, (3) recurrence of entropion. RESULTS All the AM grafts took well. The most common complication was hemorrhage below the graft, which occurred in six cases. Complete success with no lashes touching the globe was achieved in 22 of 25 (88%) lids after a minimum follow-up of 12.0 months. The mean follow-up was 17.8 months. Two cases (qualified success) had recurrent trichiasis treated successfully with electrolysis. One case with severe trachomatous upper lid entropion recurred 14 months after surgery. The AM accelerated the epithelialization of bare tarsus; this was demonstrated by lack of fluorescein staining and reversion to skin color within 2 to 3 weeks. However, AM could not prevent tarsal shrinkage. Impression cytology demonstrated that features of conjunctival epithelium were present for the first postoperative month, but this was gradually replaced by squamous metaplasia, with keratinization appearing as early as 3 weeks postoperatively. CONCLUSIONS The use of AM in a lid split procedure for correction of cicatricial entropion helps the bare tarsus epithelialize rapidly and improves the initial cosmetic result of surgery.

Recurrent corneal erosion after laser in situ keratomileusis.

Purpose. To describe how laser-assisted in situ keratomileusis (LASIK) may induce recurrent corneal erosion (RCE) syndrome and the preventive measures for avoiding this complication. Methods. A case series was used. Results. We report the development of RCE syndrome in eight eyes of six patients after LASIK. In five cases, the RCE was triggered by epithelial trauma at the time of the LASIK procedure, as evidenced by the observation of RCE occurring at the same site as the initial epithelial disturbance. In case 6, RCE occurred with undiagnosed basement membrane dystrophy. The patients responded to treatment with ocular lubricants with one patient undergoing penetrating keratoplasty for RCE after LASIK. Conclusion. LASIK can induce or precipitate RCE, and RCE should perhaps be included as a potential complication in the informed consent process. It is important to minimize epithelial damage to prevent RCE after LASIK, and measures to reduce this include adequate irrigation of the corneal surface immediately before the microkeratome pass and careful attention to flap epithelium during flap replacement. Cases in which loose epithelium is noted after LASIK should be identified as potential RCE cases, and extra care should be taken for subsequent enhancement procedures or LASIK of the second eye.

Clinical outcomes in the first two years of femtosecond laser-assisted cataract surgery.

PURPOSE To analyze outcomes of femtosecond laser cataract surgery cases in the first 2 years in an ophthalmic institution. DESIGN Nonrandomized treatment comparison with matched, historical controls. METHODS Outcomes and intraoperative events of all laser cataract surgeries (5.0- to 5.5-mm-diameter laser capsulotomies and nuclear fragmentation) at the Singapore National Eye Centre (May 2012-December 2013) were prospectively audited. The 6-weeks-postoperative unaided visual acuities (UAVA), mean absolute error (MAE), mean square error (MSE), and manifest refraction spherical equivalent (MRSE) results of surgeons with >50 laser cases were compared with controls, a random sample of manual cases with similar age, axial length, and preoperative cylinders. Statistical analysis was performed with SPSS (P < .05). RESULTS A total of 1105 eyes (803 patients) underwent laser cataract surgery by 18 surgeons. The majority were female (56.9%) and Chinese (90.9%) with mean age 66.1 ± 11.0 years. Intraoperative complications were subconjunctival hemorrhage (290, 26.2%), anterior capsule tear (9 eyes, 0.81%), posterior capsule rupture (3 eyes, 0.27%), suction loss (5 eyes, 0.45%), iris hemorrhage (1 eye, 0.09%), and endothelial incision (1 eye, 0.09%). There was no dropped nucleus. Visual outcomes of 794 laser surgeries were compared to 420 controls. The %UAVA 20/25 or better was higher in laser cases (68.6% vs 56.3%; P < .0001) but MAE (0.30 ± 0.25 diopter [D] vs 0.33 ± 0.25; P = .062) and MSE (0.16 ± 0.27 D vs 0.17 ± 0.28 D; P = .065) were not significant. MRSE comparison was significant (target plano, preoperative cylinder <1.5 D -0.08 ± 0.36 D vs -0.13 ± 0.40 D; P = .034). CONCLUSIONS Femtosecond laser cataract surgery has a low complication rate. Cases compared to controls had statistically better %UAVA ≤20/25 and MRSE, although MAE was not significant.

Descemet membrane detachment after phacoemulsification surgery: risk factors and success of air bubble tamponade.

Purpose: To evaluate the efficacy of air bubble (AB) tamponade for Descemet membrane detachment (DMD) after clear corneal incision phacoemulsification surgery and to evaluate the risk factors for DMD. Methods: This is a retrospective analysis of patients with DMD managed with AB tamponade, within 42 postoperative days (PODs), over a 4-year period. Data collected were as follows: demographics, cataract density (Lens Opacities Classification System III), visual acuity, AB technique, clinical outcome, and total surgeries over the time period. Successful end points were DM reattachment and corneal clarity. Risk factors were assessed using a case–control study, with univariate and multivariate logistic regression analyses (significance at P < 0.05). Results: Incidence rate of DMD was 0.044% per year. Sixteen patients (mean age of 76 years) had AB tamponade for DMD, with corneal clarity restored in 14 cases (87.5%; n = 11 with 1 AB procedure, n = 3 with 2 AB procedures). The main clear corneal incision was the major site of DMD (n = 14, 87.5%). Pre-AB visual acuity was 20/100 and at 1 month, 20/40. Corneal clarity occurred by 30 days (range: 4–82 days) and remained clear throughout the median follow-up of 12.9 months. Significant univariate factors were as follows: age >65 years, nuclear sclerosis grade ≥4 (Lens Opacities Classification System III), preexisting endothelial disease, and first POD corneal edema. Multivariate logistic regression analyses revealed endothelial disease (odds ratio = 18.66) and first POD edema (odds ratio = 7.88) as significant independent risk factors for DMD occurrence (P < 0.05). Conclusions: AB tamponade for DMD effectively restored corneal clarity in 87.5% of cases (14 of 16 eyes). Significant risk factors included endothelial disease and first POD corneal edema.

Steroid-induced ocular hypertension in Asian children with severe vernal keratoconjunctivitis

Background We describe clinical characteristics and risk factors for corticosteroid response in children with severe vernal keratoconjunctivitis (VKC). Design Retrospective, noncontrolled, comparative case series. Participants Patients from three tertiary centers in Singapore. Methods We reviewed patients with severe VKC (clinical grade > 2) who were on topical steroid therapy, with a minimum follow-up period of 1 year post-presentation. Logistic regression was used to determine risk factors for corticosteroid response. Main outcome measure Corticosteroid response was defined as intraocular pressure (IOP) >21 mmHg (three consecutive readings), or a rise of more than 16 mmHg from baseline, after commencement of steroid therapy in the absence of other possible causes of raised IOP. Results Forty-one of 145 (28.3%) patients developed a corticosteroid response, of which eight (5.5%) progressed to glaucoma. The overall mean age of onset of VKC was 9.9 ± 4.4 years. Longer duration of corticosteroid use (OR, 5.06; 95% CI: 1.04–25.56; P = 0.45) and topical dexamethasone 0.01% (OR, 2.25; 95% CI: 1.99–5.08; P = 0.40) were associated with corticosteroid response. Mixed type of VKC (OR, 9.76; 95% CI: 3.55–26.77; P < 0.001), the presence of limbal neovascularization of ≥ three quadrants (OR, 6.33; 95% CI: 2.36–16.97; P < 0.001), and corneal involvement (OR, 3.51; 95% CI: 1.31–9.41; P = 0.012) were significant clinical risk factors after adjusting for potential confounders such as age, sex, ethnicity, duration, and type of corticosteroid used. Conclusion Children on long-term oral corticosteroids with severe, mixed-type VKC and corneal involvement are more likely to develop corticosteroid response, and may require early treatment to prevent progression to glaucoma.

Anterior segment optical coherence tomography evaluation of the integrity of clear corneal incisions: a comparison between 2.2-mm and 2.65-mm main incisions.

PURPOSE To compare wound characteristics and integrity of the 2.2-mm and 2.65-mm clear corneal incisions. DESIGN Prospective, randomized clinical trial. METHODS Patients undergoing phacoemulsification with lens implant were randomized to receive a 2.2-mm or 2.65-mm temporal clear corneal incision. The incisions were evaluated at 2, 24, and 96 hours for gape and wound architecture using anterior segment optical coherence tomography and for integrity using the Seidel test. Squareness of an incision was calculated (ratio of the incision length to the width). RESULTS There were 30 patients in each group. Both incision sizes were watertight, although a mild internal main wound gape was detected on anterior segment optical coherence tomography in 35 eyes (58.3%) at 2 hours. The smaller wound was more square (0.81; standard deviation [SD], 0.11) than the larger wound (0.62; SD, 0.08; P < .001, t test). The mean squareness of eyes without wound gape at 2 hours (0.66; SD, 0.11) was lower than those with a wound gape (0.75; SD, 0.14; P = .008). A squareness factor of 0.72 or more had a positive predictive value for presence of wound gape at 2 hours of 79.3% and a negative predictive value of 61.3%. One side port incision with squareness of 1.39 had a mild leak at 2 and 24 hours, but no gape was seen on anterior segment optical coherence tomography. CONCLUSIONS Both the 2.2-mm and 2.65-mm clear corneal incisions clinically were competent, but the side port incision may leak. A truly square wound has a greater likelihood of being associated with internal wound gape at 2 hours after surgery, especially if the squareness factor is 0.72 or more.

Cytomegalovirus-positive corneal stromal edema with keratic precipitates after penetrating keratoplasty: a case-control study.

Purpose: To identify differences between cytomegalovirus (CMV)-positive and CMV-negative eyes presenting as suspected endothelial graft rejection after penetrating keratoplasty (PK). Methods: A retrospective consecutive case–control series. Aqueous humor samples of all eyes with corneal stromal edema and keratic precipitates (KPs) after PK, seen at the Singapore National Eye Centre from 2007 to 2010, were analyzed for CMV DNA by polymerase chain reaction. Their charts were reviewed for demographic data, medical and ocular history, best-corrected visual acuity, intraocular pressure, anterior segment clinical findings, and therapy. Results: Of 11 eligible eyes (11 patients), 7 were CMV positive. All eyes were negative for herpes simplex virus and varicella zoster virus. The 2 groups were similar in age, gender, and previous ocular surgery. The main differences were the presence of extensive heavily pigmented KPs, Descemet membrane folds, and the absence of vascularization of the donor in CMV-positive eyes (100% vs. 0%, P = 0.003, Fisher exact test). All the CMV-positive eyes were treated with ganciclovir (5 systemic, 2 topical), and the control eyes received immunosuppression. However, all the grafts failed. Best-corrected visual acuity at the last visit was worse than 20/400 in all except 1 control eye, which had a follow-up of 30 months. Conclusions: There is a high prevalence of CMV infection in eyes that develop corneal stromal edema with KPs after PK. Heavy endothelial pigmentation, Descemet membrane folds, and the absence of donor vascularization may aid in the diagnosis of CMV in the event that aqueous analysis is not possible.