A cross-sectional control study done by researchers from the Massachusetts Eye and Ear Infirmary, evaluating corneal endothelial cell density in patients with dry-eye disease compared to an age-matched control group, found significant reduction in corneal ECD in dry-eye disease patients that correlates with clinical severity.
This study involved 90 eyes of 45 patients with moderate to severe dry-eye disease (aged 53.7 ±9.8 years) and 30 eyes of 15 normal controls (aged 50.7 ±9.8 years). All subjects had a complete ophthalmic evaluation, including symptom assessment using the Ocular Surface Disease Index and corneal fluorescein staining. In addition, laser scanning in vivo confocal microscopy was performed to measure the density of the following parameters in the central cornea: endothelial cells; sub-basal nerves; and sub-basal immune dendritic cells.
Corneal ECD was significantly lower in the dry-eye disease group (2,595.8 ±356.1 cells/mm2) than in the control group (2,812.7 ±395.2 cells/mm2; p=0.046). The dry-eye disease group showed significantly lower corneal sub-basal nerve density (17.1 ±6.9 mm/mm2) compared to the control group (24.7 ±4.4 mm/mm2; p<0.001). Dendritic cell density was significantly higher in the dry-eye group than in the controls (111.7 ±137.3 vs. 32 ±24.2 cells/mm2; p=0.002). There were statistically significant correlations between corneal ECD and dry-eye severity parameters including the OSDI score (rs=-0.26; p=0.03) and corneal fluorescein staining (rs=-0.28; p=0.008).
Am J Ophthalmol 2015;159:1022-1026.
Kheirkhah A, Saboo U, Abud T, Dohlman T, et al.
OCT-3 to Evaluate Temporal Retinal Thickness
A prospective study evaluating temporal macular retinal thickness using optical coherence tomography-3-generated superior-to-inferior retinal thickness (S/I RT) ratios successfully reproduced the structural damage in eyes with early and advanced glaucoma field defects.
Forty normal eyes, 40 eyes with early glaucomatous visual field defects and 33 eyes with advanced visual field defects were included in this study. All participants underwent complete ocular and visual field examinations and OCT-3 imaging on the same day. A 3x3-mm area temporal to the foveal reflex was scanned with the OCT-3 using six horizontal, equally spaced raster lines. Retinal thickness was evaluated at points 500 µm apart for each line and S/I RT ratio computed between similar points above and below the fovea for each patient. One-way ANOVA was used to compare S/I RT ratio between the normal, early and advanced glaucoma eyes.
Average retinal thickness increased progressively as points temporal to the fovea were scanned. There was a statistically significant difference between the average superior and inferior retinal thickness at points 1,500, 2,000 and 2,500 µm temporal to the fovea in both early and advanced glaucoma eyes (p<0.05) with corresponding significant differences in the S/I RT ratios when compared with the normal participants (p<0.017). This suggests OCT-3 can complement optic disc scanning protocols in diagnosing glaucoma at an early age.
J Glaucoma 2015;24:257-261.
Sihota R, Naithani P, Sony P, Gupta V.
Using Omega-3s to Improve Contrast Sensitivity in MGD
Indian researchers at the World Cornea Congress presented results from a study concluding that oral supplementation with omega-3 fatty acids significantly improves contrast sensitivity under both photopic and mesopic testing conditions in patients with moderate meibomian gland dysfunction. Tear-film stability was also improved significantly with omega-3 FA supplementation, although no effect was seen on aqueous tear production.
Utilizing a prospective study design, 60 patients with moderate MGD were allocated alternately to treatment and control groups. Both groups received warm compresses, lid massage and artificial tear substitutes. The treatment group also received oral supplements of 1.2 g omega-3 FA per day. All parameters were recorded at baseline and at 12 weeks, including Ocular Surface Disease Index scores, contrast sensivity testing at three, six, 12 and 18 cycles per degree, tear breakup time, Schirmer test I without anesthesia, corneal and conjunctival staining scores and meibum quality and expressibility.
At the end of 12 weeks, significant improvement in contrast sensitivity was seen in the treatment group in seven of the eight testing conditions (three, six, 12 and 18 CPD photopic and six, 12 and 18 CPD mesopic), whereas in the placebo group, significant improvement was only seen in three of the eight testing conditions (three CPD photopic; six and 18 CPD mesopic). Ocular Surface Disease Index, tear breakup time, ocular surface staining and meibum quality and expressibility improved significantly in both groups, but more so in the treatment group. Schirmer scores showed no significant improvement in either group.
Malhotra C, Singh S, Chakma P, Jain A.
Sustained IOP Rise After Intravitreal Anti-VEGF
An analysis of current literature evaluating sustained and delayed elevation of IOP in patients receiving intravitreal anti-VEGF therapy for neovascular age-related macular degeneration suggests that it is likely a multifactorial process. Within the literature, the incidence of sustained elevation of IOP in patients with neovascular AMD varied from 3.45 percent to 11.6 percent and few patients required surgical management to control IOP. Possible risk factors associated with sustained and delayed elevation of IOP include, but are not limited to, history of glaucoma; phakia; history of glucocorticoid use; and/or extended treatment duration. There are multiple theories explaining the pathogenesis of sustained elevation of IOP, including microparticle obstruction of the trabecular meshwork, intraocular inflammation and transient elevation of IOP. The lack of an effect in some studies may be due to a small cumulative number of injections and/or short follow-up periods; small study size may also be a limiting factor, as this may be a rare event.
Although there may be insufficient data to conclusively determine that intravitreal injection of VEGF inhibitors results in sustained elevation of IOP, the current body of literature supports this theory. Further studies to prospectively investigate sustained elevation of IOP in large, randomized control trials might lead to better understanding of the long-term adverse events associated with intravitreal anti-VEGF.
Dedania V, Bakri S.
Comparative Cost-Effectiveness Of Glaucoma Treatments
New York doctors assessed the cost-effectiveness of the 350-mm2 Baerveldt implant (tube) insertion and trabeculectomy with mitomycin-C with maximal medical treatment, showing that–assuming a willingness to pay $50,000 per quality-adjusted life-years (QALYs)–tube insertion and trabeculectomy are cost-effective compared with medical treatment alone. Trabeculectomy, however, is cost-effective at a substantially lower cost per QALY compared with tube insertion.
The doctors utilized a Markov cohort model with a five-year time horizon to study a hypothetical cohort of 100,000 patients who required glaucoma surgery. The main outcomes and measures were QALYs gained, costs from the societal perspective and the incremental cost-effectiveness ratio of medical treatment, tube insertion and trabeculectomy. Costs were identified from the Centers for Medicare & Medicaid Current Procedural Terminology and Ambulatory Payment Classification reimbursement codes and Red Book medication costs. The QALYs were based on visual field and visual acuity outcomes. The hypothetical societal limit to resources was included, using a willingness-to-pay threshold of $50,000 per QALY. Costs and utilities were discounted at 3 percent per year. Uncertainly was assessed using deterministic sensitivity analyses.
The mean costs for medical treatment, tube insertion and trabeculectomy were $6,172, $10,075 and $7,872; these amounts resulted in a cost difference of $1,700 (95 percent confidence interval; $1,644 to $1,770) for medical treatment vs. trabeculectomy, $3,904 (95 percent CI; $3,858 to $3,953) for medical treatment vs. tube insertion and $2,203 (95 percent CI; $2,121 to $2,261) for trabeculectomy vs. tube insertion. The mean five-year probability of blindness was 4 percent for both surgical procedures and 15 percent for medical treatment. The utility gained after medical treatment, tube insertion and trabeculectomy was 3.10, 3.38 and 3.30 QALYs, respectively. The incremental cost-effectiveness ratio was $8,289 per QALY for trabeculectomy vs. medical treatment; $13,896 per QALY for tube insertion vs. medical treatment; and $29,055 per QALY for tube insertion vs. trabeculectomy. The cost-effectiveness of each surgical procedure was most sensitive to early and late surgical failure rate and was minimally affected by adverse events, rate of visual field progression or medication costs.
JAMA Ophthalmol 2015;133:560-567.
Kaplan R, de Moraes C, Cioffi G, Al-Aswad L, et al.