Jason C.S. Yam

Ultraviolet light and ocular diseases.

The objective of this study is to review the association between ultraviolet (UV) light and ocular diseases. The data are sourced from the literature search of Medline up to Nov 2012, and the extracted data from original articles, review papers, and book chapters were reviewed. There is a strong evidence that ultraviolet radiation (UVR) exposure is associated with the formation of eyelid malignancies [basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)], photokeratitis, climatic droplet keratopathy (CDK), pterygium, and cortical cataract. However, the evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, ocular surface squamous neoplasia (OSSN), and ocular melanoma remained limited. There is insufficient evidence to determine whether age-related macular degeneration (AMD) is related to UV exposure. It is now suggested that AMD is probably related to visible radiation especially blue light, rather than UV exposure. From the results, it was concluded that eyelid malignancies (BCC and SCC), photokeratitis, CDK, pterygium, and cortical cataract are strongly associated with UVR exposure. Evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, OSSN, and ocular melanoma remained limited. There is insufficient evidence to determine whether AMD is related to UV exposure. Simple behaviural changes, appropriate clothing, wearing hats, and UV blocking spectacles, sunglasses or contact lens are effective measures for UV protection.

Bilateral Deepening of Upper Lid Sulcus From Topical Bimatoprost Therapy

PURPOSE To report a new adverse effect related to treatment with bimatoprost. METHOD Case report. A 43-year-old Asian female with bilateral glaucoma was noticed to have bilateral deepening of upper lid sulcus 3 months after beginning treatment with bimatoprost 0.03%. RESULTS Bimatoprost was discontinued due to cosmetic reasons, and there was improvement of the lid sulcus deepening bilaterally 4 weeks after stopping the drug. CONCLUSIONS Deepening of upper lid sulcus is one of the adverse effects related to treatment with bimatoprost. This effect may be more prominent in Asians who have relatively full upper lid sulcus.

Corneal collagen cross-linking demarcation line depth assessed by Visante OCT After CXL for keratoconus and corneal ectasia.

PURPOSE To report the demarcation line depth after corneal collagen cross-linking (CXL) for keratoconus and postoperative LASIK ectasia with Visante (Carl Zeiss Meditec) optical coherence tomography (OCT) and investigate correlations between this depth and preoperative parameters and postoperative visual and keratometry outcomes. METHODS Retrospective interventional case series of 40 eyes with keratoconus or postoperative LASIK ectasia treated with riboflavin ultraviolet-A CXL. Ophthalmic evaluation included uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal topography (Pentacam, Oculus Optikgeräte GmbH), and postoperative anterior segment OCT. Correlation analyses were performed. Statistical significance was indicated by P<.05. RESULTS At 6 months postoperative, mean demarcation line depth was 281.4±53.3 μm. Thinner minimal corneal thickness (r=0.413, P=.008), older age (r=-0.490, P=.001), higher grading of ectasia (for both keratoconus and postoperative LASIK ectasia) (r=-0.332, P=.044), female sex (r=0.343, P=.030), postoperative LASIK ectasia (r=-0.420, P=.007), and longer duration of disease (r=-0.377, P=.023) were correlated with shallower demarcation line depth. Forward stepwise multiple linear regression analysis showed that among all preoperative factors, minimal corneal thickness (standardized β=0.473, P=.003) and age (standardized β=-0.317, P=.036) were significantly associated with demarcation line depth. The CXL demarcation line depth and change in CDVA (r=-0.16, P=.325) and change of the steepest keratometry at 6 months (r=0.084, P=.637) were not correlated. CONCLUSIONS The Visante OCT can be used for assessing CXL demarcation line depth. The demarcation line depth may decrease with the severity of ectasia and age.

Association between hyperglycemia and retinopathy of prematurity: a systemic review and meta-analysis

As the role of hyperglycemia in the development of retinopathy of prematurity (ROP) has not been well established, a meta-analysis of the association between hyperglycemia and ROP was conducted. Studies were identified through literature search in MEDLINE and EMBASE up to June 20, 2014 with keywords related to “hyperglycaemia” and “ROP”. Nine eligible studies involving 1939 neonates with 509 cases of ROP were included. Unadjusted analyses showed that hyperglycemia was significantly associated with ROP (Odds ratio [OR] = 4.16, P<0.0001). Comparing with the control, subjects in the ROP group had a significantly longer duration of hyperglycemia (Standardized mean difference [SMD] = 1.21, P< 0.0001), and higher mean glucose level. (SMD = 0.88, P = 0.0004) However, when combining the adjusted OR (after adjustment for birth weight, gestational age and other factors) provided from individual studies, only borderline significant association were observed on duration of hyperglycemia with ROP (adjusted OR 1.08, P = 0.03); and no significant association on mean glucose level with ROP (adjusted OR = 1.08, P = 0.15). Hence, hyperglycemia cannot be definitely considered as a risk factor for ROP, and further studies should adjust for potential confounding factors to clarify this association.

Risk of recurrence of retinopathy of prematurity after initial intravitreal ranibizumab therapy

We report our experience with the use of intravitreal ranibizumab for the treatment of retinopathy of prematurity (ROP). A retrospective review was performed on 138 consecutive infants screened at a single centre over 18 months. Intravitreal ranibizumab was offered in selected cases requiring treatment, such as aggressive posterior ROP or poor mydriasis. 2 eyes of 1 infant received intravitreal ranibizumab alone and 8 eyes of 5 infants received combined intravitreal ranibizumab and laser therapy. 3 out of 8 eyes treated initially with intravitreal ranibizumab monotherapy had persistent disease requiring laser therapy, and 3 out of 5 eyes with initial regression suffered disease recurrence at a mean of 7.6 weeks post-injection. 2 eyes treated first with laser followed by intravitreal ranibizumab had disease regression without recurrence. Our cohort demonstrate a significant rate of persistent disease and recurrence in ROP eyes treated initially with intravitreal ranibizumab monotherapy, which is greater and earlier than that reported for intravitreal bevacizumab in the BEAT-ROP study. Intravitreal ranibizumab may be useful as an initial treatment in selected cases of ROP when laser therapy as first line is suboptimal. However, close monitoring is important and adjunctive laser therapy may subsequently be needed in a majority of cases.

Association of Gestational Hypertensive Disorders with Retinopathy of prematurity: A Systematic Review and Meta-analysis

The role of gestational hypertensive disorders, which includes both pre-eclampsia and gestational hypertension, in the development of retinopathy of prematurity (ROP) has been controversial. Therefore, this systematic review and meta-analysis is to evaluate the association between gestational hypertensive disoders and ROP. Eligible studies published up to June 5, 2016 were identified from MEDLINE and EMBASE that evaluated the association between the two conditions. Totally 1142 published records were retrieved for screening, 925 of them eligible for detailed evaluation. Finally 19 studies involving 45281 infants with 5388 cases of ROP met our criteria for meta-analysis. Gestational hypertensive disorders were not associated with ROP (unadjusted OR: 0.89; P = 0.38; adjusted OR: 1.35; P = 0.18). Subgroup analyses also revealed no significant association between ROP with pre-eclampsia (unadjusted OR: 0.85; P = 0.29; adjusted OR:1.29; P = 0.28) or with gestational hypertension (unadjusted OR: 1.10; P = 0.39; adjusted OR: 1.25; P = 0.60) separately. Sensitivity analysis indicated our results were robust. We concluded no significant association between gestational hypertensive disorders and ROP. More large scale well-conducted prospective cohorts on the topic are needed.

Prognostic factors for visual outcomes after crosslinking for keratoconus and post-LASIK ectasia.

Purpose To determine the prognostic factors associated with better visual outcomes 1 year after corneal collagen crosslinking (CXL) for keratoconus and post–laser-assisted in situ keratomileusis (LASIK) ectasia. Methods The study cohort comprised 75 eyes from 50 patients with keratoconus or post-LASIK ectasia who underwent CXL. The outcomes measured were visual response, change of corrected distance visual acuity (CDVA), and CDVA 1 year after CXL. The cohort was divided into groups based on the change in CDVA postoperatively. The visual responders were the patients with visual improvement of at least 1 line Snellen CDVA at 1 year postoperatively, and the visual nonresponders were the patients with a gain of less than 1 line, no change, or loss of Snellen lines CDVA at 1 year postoperatively. Univariate analysis was performed to determine the association between the preoperative parameters and visual response. Correlation analyses and forward stepwise regression analyses were performed to evaluate the effect of the preoperative factors on CDVA and the improvement of CDVA at 1 year. Results There was significant visual improvement from 0.257 ± 0.29 logMAR to 0.159 ± 0.208 logMAR (p<0.001; paired t test) at 1 year postoperatively with a mean change in CDVA of −0.098 ± 0.151 logMAR. The visual responders (46 cases, 61.3%) had poorer preoperative CDVA (p = 0.023), thinner minimal corneal thickness (p = 0.041), and thinner central corneal thickness (p = 0.012) compared to the visual nonresponders (29 cases, 38.7%). Forward stepwise multiple linear regression analysis indicated that the preoperative CDVA significantly affected both the postoperative change in CDVA (standardized β = 0.614; p<0.001) and the postoperative CDVA (standardized β = 0.893; p<0.001). Conclusions Crosslinking for keratoconus and post-LASIK ectasia can lead to significant visual improvement 1 year after treatment. The preoperative CDVA was a significant prognostic factor for the visual outcome.

Predictive Factors Affecting the Short Term and Long Term Exodrift in Patients with Intermittent Exotropia after Bilateral Rectus Muscle Recession and Its Effect on Surgical Outcome

Purpose. To determine the predictive factors that affect short term and long term postoperative drift in intermittent exotropia after bilateral lateral rectus recession and to evaluate its effect on surgical outcome. Methods. Retrospective review of 203 patients with diagnosis of intermittent exotropia, who had surgical corrections with more than 3 years of followup. Different preoperative parameters were obtained and evaluated using Pearsons correlation analysis. Results. The proportion of exodrift increased from 62% at 6 weeks to 84% at 3 years postoperatively. The postoperative drift was 4.3 ± 8.1 PD at 6 weeks, 5.8 ± 8.4 PD at 6 months, 7.2 ± 8.3 PD at 1 year, 7.4 ± 8.4 PD at 2 years, and 7.7 ± 8.5 PD at 3 years. Preoperative deviation and initial overcorrection were significant factors affecting the postoperative drift at 3 years (r = 0.177, P = 0.011, r = −0.349, and P < 0.001, resp.). Conclusions. Postoperative exodrift along three years occurs in a majority of patients after bilateral lateral rectus recession for intermittent exotropia. The long term surgical success is significantly affected by this postoperative exodrift. A larger preoperative deviation and a larger initial overcorrection are associated with a larger early and late postoperative exodrift.

Reduced Cross-linking Demarcation Line Depth at the Peripheral Cornea After Corneal Collagen Cross-linking

PURPOSE To compare the corneal collagen cross-linking (CXL) demarcation line depth between the central and peripheral cornea after cross-linking using anterior segment optical coherence tomography. METHODS Retrospective interventional case series of 38 eyes with keratoconus or postoperative LASIK ectasia treated with riboflavin ultraviolet A CXL (UV-X, IROC). CXL demarcation line depth, corneal thickness, and the ratio of the CXL demarcation line depth to the corneal thickness were measured using anterior segment optical coherence tomography at the central cornea and at 2 and 4 mm from the corneal center in four regions: temporal, nasal, superior, and inferior. The CXL demarcation line depths at the center and periphery were compared using the Friedman test. RESULTS The CXL demarcation line was deepest in the central cornea (302 μm; range: 180 to 397 μm) and was reduced progressively toward the peripheral cornea, at nasal 2 mm (289.5 μm; range: 125 to 370 μm), at nasal 4 mm (206.5 μm; range: 100 to 307 μm), at temporal 2 mm (278.5 μm; range: 128 to 375 μm), and at temporal 4 mm (194 μm; range: 80 to 325 μm) (P<.001). The penetration proportion was greatest at the central cornea (64.8%; range: 44% to 80%) and was decreased toward the periphery, at nasal 2 mm (53.8%; range: 30% to 74%), at nasal 4 mm (33.8%; range: 19% to 53%), at temporal 2 mm (54.1%; range: 29% to 77%), and at temporal 4 mm (34.1%; range: 15% to 54%) (P⩽.001). CONCLUSIONS Both the CXL demarcation line depth and its proportion over the corneal thickness were greater at the central cornea than the peripheral cornea.

Ocular demodicidosis as a risk factor of adult recurrent chalazion

Purpose: To report Demodex infestation in adult recurrent chalazion and its clinical response to weekly lid scrub with 50% tea tree oil (TTO) and daily lid scrub with tea tree shampoo. Methods: This is a retrospective review of 30 adult patients (48 eyes) who presented with recurrent chalazion within 6 months after conventional treatment. Demodex was detected by random lash sampling and microscopic examination. Patients with confirmed ocular Demodex infestation were treated with weekly lid scrub with 50% TTO and daily lid scrub with tea tree shampoo. The study is limited by the lack of a control group. Results: The mean age of patients was 39.1 ± 10.2 years (range 18-69). The mean follow-up of patients is 10.0 ± 3.0 months (range 6-24 months). Among 48 eyes with recurrent chalazion, Demodex mites were found in 35 (72.9%). Recurrent chalazion was found to be associated with ocular demodicidosis (Fisher exact test, p = 0.017). Tea tree oil treatment was given to 31 eyes with recurrent chalazion associated with Demodex infestation. Among the treatment group, all cases except one had no recurrence after the TTO treatment. The success rate of preventing recurrence is 96.8%. Treatment of TTO was found to be associated with preventing recurrence of chalazion associated with Demodex infestation (Fisher exact test, p = 0.002). Conclusions: The possibility of demodicidosis should be considered in adults presenting with recurrent chalazia. Tea tree oil eyelid scrubs is an effective treatment in preventing recurrence.