Much of confusion exists in the literature because central retinal vein occlusions and branch retinal vein occlusions (BRVOs) are often grouped and studied together. The natural history and the complication rate for each entity differ. The treatments and their results vary from one condition to the other. This article talks about the use of Intra Vitreal Triamcinolone Acetonide (IVTA) and Intra Vitreal Bevacizumab (IVB) injections to treat macular edema with BRVO.

The aim of the study was to compare visual outcomes after intravitreal triamcinolone acetonide (IVTA) injection and intravitreal bevacizumab (IVB) administration for treatment of macular edema associated with branch retinal vein occlusion (BRVO).

A retrospective comparative case series of 134 consecutive patients that were treated with either IVTA or IVB for macular edema caused by BRVO. Visual acuity at baseline and 1, 3, 6, 9, and 12 months, and central macular thickness measured by OCT at baseline and 1, 3, 6, and 12 months. The time to recurrence of macular edema after treatment was also analyzed.

In results the Visual acuity (Snellen equivalent) improved significantly from 0.87 log MAR (0.14) to 0.49 log MAR (0.33) in the IVTA group, and from 0.91 log MAR (0.13) to 0.45 log MAR (0.36) in the IVB group 12 months after injection ( p < 0.001). Central macular thickness decreased significantly from 491.0 µm to 255.8 µm in the IVTA group, and from 477.4 µm to 218.9 µm in the IVB group 12 months after injection ( p < 0.001). In between-group comparisons, neither visual acuity ( p = 0.892) nor macular thickness ( p = 0.612) improvements were statistically significantly different. In the IVTA-all group, recurrence of macular edema occurred in 7.6% of patients at a mean of 12.6 months postoperatively, and the average number of injections was 1.08. In the IVB-all group, 26.0% of patients suffered recurrences at a mean of 5.3 months after treatment, and received a mean of 1.89 injections. Recurrence was more frequent in the IVB group compared to the IVTA group (Kaplan–Meier survival analysis log-rank test, p < 0.0001).

The study concluded that IVTA and IVB injections were similarly effective for improving visual acuity in patients with macular edema secondary to BRVO. However, the IVTA group showed longer mean improvement duration and less disease recurrence, and required fewer injections than the IVB group.

Adapted from: Graefe's Archive for Clinical and Experimental Ophthalmology, Feb 25, 2010

Diabetic macular edema is the result of retinal micro- vascular changes that occur in patients with diabetes. Thickening of the basement membrane and reduction in the number of pericytes is believed to lead to increased permeability and incompetence of retinal vasculature. This article talks about the use Difluprednate ophthalmic emulsion in improving retinal thickness .

The aim of this study was to evaluate the efficacy of treatment of refractory diabetic macular edema (DME) after Viterectomy with difluprednate ophthalmic emulsion 0.05% and to compare this treatment with sub-Tenon's injection of triamcinolone (STTA).

This study enrolled patients with refractory diabetic macular edema that persisted despite pars plana Viterectomy in our clinic. In all subjects, more than 3 months had passed since prior treatment. Eleven eyes in ten subjects were treated with STTA (STTA group), and 11 eyes in seven subjects were treated with difluprednate ophthalmic emulsion 0.05% 4 times daily for the first month and then twice daily for 2 months (eye drop group).

The results showed that, in the eye drop group, mean VA (± SD) was 0.67 ± 0.35 log MAR and mean retinal thickness was 500.6 ± 207.7 µm at baseline. After 3 months of treatment, mean VA was 0.67 ± 0.29 and mean retinal thickness had decreased to 341.2 ± 194.8 µm. The mean minimum value of RT during the treatment period was 300.6 ± 123.2 µm, and significantly lower than that at baseline (Mann–Whitney U test: P = 0.003). In the STTA group, mean VA (± SD) was 0.67 ± 0.35 log MAR, and mean retinal thickness was 543.3 ± 132.6 µm at baseline. After 3 months of treatment, mean VA was 0.49 ± 0.67, and mean retinal thickness had decreased to 378.6 ± 135 µm. The mean minimum value of RT during the treatment period was 349.9 ± 113.8 µm, and significantly lower than at baseline (Mann–Whitney U test: P = 0.003). The rate of effective improvement in RT did not differ between the eye drop group (73%) and STTA group (84%) (Fisher's exact test: P = 1).

Thus, the study concludes that comparable improvements of retinal thickness were observed in the STTA and eye drop groups. Instillation of difluprednate ophthalmic emulsion 0.05% is a safe and effective treatment that does not require surgical intervention and does not produce severe side-effects.

Adapted from : Graefe's Archive for Clinical and Experimental Ophthalmology, Feb 25, 2010.

Retinitis pigmentosa (RP) is a group of inherited disorders characterized by progressive peripheral vision loss and night vision difficulties (nyctalopia) that can lead to central vision loss. This article talks about the outcomes of refractive surgeries in patients with Retinitis Pigmentosa.

The purpose of this study was to evaluate the refractive outcomes and safety of laser refractive surgery in a group of myopic patients with retinitis pigmentosa (RP).

This was a multicenter, retrospective, non-comparative, interventional case series. A total of 32 eyes of 16 patients with RP with at least 18 months of follow-up were treated with laser refractive surgery photorefractive keratectomy [PRK], laser sub-epithelial keratectomy [LASEK]). Refractive outcomes, complete eye examination, corneal topography, and retinal sensitivities were evaluated during follow-up. Mean follow-up was 28.3 months (minimum 18, maximum 50). Mean patient age was 29.6 years (range 24–54). Mean best-corrected visual acuity (BCVA) was 0.75 preoperatively.

Eighteen months after surgery, mean uncorrected visual acuity (UCVA) was 0.8±1 line (p=0.02); mean BCVA was 0.85±1 line (p<0.0005) with mean spherical equivalent of –0.16 D. Corneal complications were not detected during follow-up; corneal topography did not show corneal ectasia in any patient after surgery. During follow-up visits, no development or progress of macular edema was noted in any eye. Retinal sensitivities increased after surgery; there were no significant changes in electroretinogram amplitude.

The study concluded saying that the mean UCVA and BCVA 18 months after surgery were higher than preoperative BCVA. All patients were safely treated without any significant complications. Our results support the safety of performing PRK and LASEK in patients with Retinitis pigmentosa (RP).

Adapted from : Eur J Ophthalmol 2010; 20: 271 – 275.

Bacterial keratitis is a sight-threatening process. A particular feature of bacterial keratitis is its rapid progression; corneal destruction may be complete in 24-48 hours with some of the more virulent bacteria. Corneal ulceration, stromal abscess formation, surrounding corneal edema, and anterior segment inflammation are characteristic of this disease . Currently fourth generation Antibiotics are been used for the treatment of Bacterial keratitis and this study was done to determine the antibiotic sensitivity pattern of fourth generation fluoroquinolones.

The purpose of the study was to study the microbiological profile of bacterial keratitis in Northern India and to determine the antibiotic sensitivity pattern of bacterial keratitis isolates to fourth-generation fluoroquinolones.

The Laboratory records of all consecutive cases of clinically suspected bacterial corneal ulcers were retrospectively reviewed. Data noted included microorganism isolated and antibiotic culture sensitivity to cefazolin, tobramycin, gatifloxacin, and moxifloxacin . In vitro susceptibility toward individual antibiotics was determined and compared with the potential in vitro susceptibilities to cefazolin-tobramycin, cefazolin-gatifloxacin, and cefazolin-moxifloxacin combinations.

A total of 292 bacterial isolates were identified. Of these, 255 (87.3%) were Gram-positive and 37 (12.7%) were Gram-negative. Staphylococcus epidermidis (n=227, 77.7%) was the most common organism. Overall susceptibility of isolates was 95.52% to gatifloxacin, 92.83% to moxifloxacin, 90.07% to tobramycin, and 83.56% to cefazolin (p<0.000). Organisms which showed resistance to fourth-generation fluoroquinolones included Staphylococcus epidermidis , Pseudomonas aeruginosa, viridans streptococci, Streptococcus pneumoniae, Staphylococcus aureus, and Escherichia coli. Susceptibilities to gatifloxacin and moxifloxacin were comparable with each other (p=0.312) and with potential susceptibilities to cefazolin-tobramycin (p=0.479), gatifloxacin-cefazolin (p=0.134), and moxifloxacin-cefazolin (p=0.412) combinations.

Thus, Monotherapy with moxifloxacin or gatifloxacin can be an effective alternative to cefazolin-tobramycin combination as a first-line empirical therapy for bacterial keratitis. The addition of cefazolin to a fourth-generation fluoroquinolone is of limited value.

Adapted from : Eur J Ophthalmol 2010; 20: 300 – 305.

Vascular endothelial growth factor ( VEGF ) is a chemical signal produced by cells that stimulates the growth of new blood vessels. VEGF's normal function is to create new blood vessels during embryonic development, new blood vessels after injury, and new vessels to bypass blocked vessels . When VEGF is over expressed, it can contribute to disease over expression of VEGF can cause vascular disease in the retina of the eye and other parts of the body. This study talks about the use of Simvastatin in inhibiting VEGF.

While statins have an anti-angiogenic property, their underlying mechanisms are not fully understood. We investigated intracellular mechanisms of simvastatin-mediated reduction in VEGF-induced signalings.

The effects of simvastatin on cell proliferation and viability were evaluated by [ 3 H]-thymidine incorporation in retinal endothelial cells (RECs) and cell counting. The impact of simvastatin on VEGF-induced phosphorylation of p44/42 mitogen-activated protein (MAP) kinase, myosin light chain (MLC), and VEGF-receptor (VEGFR) 2 were examined by Western blotting. Involvement of the mevalonate pathway in VEGF-induced signaling was also examined.

The results showed that   Simvastatin (1 and 10 µM) suppressed VEGF-induced RECs proliferation in a concentration-dependent manner, without affecting cell viability. Simvastatin significantly inhibited VEGF-induced phosphorylation of VEGFR2 and its downstream mediators, p44/42 MAP kinase and MLC. Mevalonate completely reversed VEGF-induced VEGFR2 phosphorylation, but only partially reversed the phosphorylation of p44/42 MAP kinase and MLC.

These data indicate that simvastatin exerts its anti-angiogenic effects through the reduction of VEGFR2 phosphorylation in RECs at least in part. However, there seems to be both mevalonate-dependent and independent pathway in simvastatin's anti-angiogenic property.

Adapted from : Graefe's Archive for Clinical and Experimental Ophthalmology, Feb 13, 2010