Optical Scattering from Vitreous Floaters.

Vitreous "floaters" are a common entoptic phenomenon that can result in significant reduction in quality of life in a proportion of sufferers. The authors use a computational mathematical model based on Fourier optics and reflection and transmission coefficients calculated for a planar type II collagen opacity suspended in aqueous to show that floaters are perceived by the patient through interference effects that result in significant variations in intensity on the retina when viewing a constant brightness surface. The model also predicts that backscattered intensity from floaters is ten thousand to one million times lower than the variations in intensity produced on the retina, which demonstrates that the visible effects of floaters for the patient can be highly significant, whereas clinical observation of the vitreous may be entirely unremarkable. Importantly, the results also demonstrate that floaters do not need to be opaque to cause symptoms, with only small differences in refractive index between the floater material and the surrounding vitreous needed to produce significant optical effects. The model predicts that pupil size is an important factor in determining the severity of symptoms from floaters, with constricted pupils giving much greater effect than dilated pupils. Finally, the authors' model predicts that floaters degrade contrast sensitivity function, with greatest degradation occurring in the 5-40 cycles per degree spatial frequency range and that the effects of shadowing caused by floaters are very strongly correlated to the predicted degradation of contrast sensitivity function. Bioelectromagnetics. 43:90-105, 2022. © 2021 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

Successful treatment of choroidal neovascularization secondary to sorsby fundus dystrophy with intravitreal bevacizumab.

PURPOSE: The purpose of this study was to investigate the response of choroidal neovascularization (CNV) in Sorsby fundus dystrophy to intravitreal bevacizumab. METHODS: Three eyes of 2 patients with CNV as a result of Sorsby fundus dystrophy were treated with intravitreal bevacizumab injections (0.05 mL, 1.25 mg bevacizumab). Best-corrected visual acuity, optical coherence tomography, and/or fluorescein angiography before and after treatment were assessed. RESULTS: At 33-month follow-up, after 6 intravitreal bevacizumab injections in 1 eye of the first patient, best-corrected visual acuity improved from 1.00 logarithm of the minimum angle of resolution to 0.93 logarithm of the minimum angle of resolution; there was no evidence of CNV activity on optical coherence tomography or on fluorescein angiography. At 6 weeks after 1 injection in the first patient's fellow eye, best-corrected visual acuity was stabilized at 0.00 logarithm of the minimum angle of resolution without any CNV activity on optical coherence tomography or on fluorescein angiography. At 12-week follow-up, after 1 intravitreal bevacizumab injection in 1 eye of the second patient, best-corrected visual acuity improved from 1.00 logarithm of the minimum angle of resolution to 0.00 logarithm of the minimum angle of resolution; there was no evidence of CNV activity on optical coherence tomography or on fluorescein angiography. CONCLUSION: Intravitreal bevacizumab should be considered as a safe and effective treatment for CNV secondary to Sorsby fundus dystrophy.

Prognostic factors that determine visual outcome following cataract surgery complicated by vitreous loss.

PURPOSE: To identify prognostic factors that determine visual outcome following phacoemulsification cataract surgery complicated by vitreous loss. METHODS: A retrospective cohort study. All cases of vitreous loss during phacoemulsification surgery at a university hospital, between June 2000 and December 2005, were identified from the hospital computer database. By reviewing the medical notes, preoperative, intraoperative, and postoperative data were collected. Outcome of interest was presence of poor visual outcome (best-corrected visual acuity [BCVA] <6/12). Chi-square and Mann-Whitney U tests were used to compare groups of poor and good visual outcome. RESULTS: A total of 230 consecutive cases (eyes) were identified; medical notes were available for 228. Mean patient age was 78.4 years (SD 11); median follow-up 13.4 weeks (range 1-203). In multivariable logistic regression analysis poor visual outcome was independently associated with poor preoperative vision (BCVA <6/12) (OR 3.78, 95% CI 1.76-8.11), age-related macular degeneration (OR 3.04, 95% CI 1.16-8.00), cystoid macular edema (OR 3.85, 95% CI 1.29-11.51), and secondary pars plana vitrectomy (PPV) for nuclear fragment loss (OR 4.42, 95% CI 1.03-19.02). Primary PPV for nuclear fragment loss, age >70, ocular comorbidity, axial length, vitreous loss during irrigation/aspiration, or lens implantation, anterior chamber lens, and secondary lens implantation were not significant associations (p>or= 0.05). In 33 (14.5%) eyes BCVA was reduced by at least one Snellen line compared to before surgery. CONCLUSIONS: Poor visual outcome was associated with poor preoperative vision, age-related macular degeneration, cystoid macular edema, and secondary PPV following nuclear fragment loss. Primary PPV for nuclear fragment loss was not a significant association.

Scleral hydraulic conductivity and macromolecular diffusion in patients with uveal effusion syndrome.

PURPOSE: To determine whether uveal effusion syndrome (UES) is caused by altered scleral permeability to water and large molecules. METHODS: Transscleral water movement was measured using surgically removed sclera clamped in a modified Ussing chamber and connected to a water column set at intraocular pressure. Sclera was also clamped between two hemichambers, and transscleral diffusion of FITC-dextrans (4.4-77 kDa) was measured with a spectrophotometer. Clinical data were prospectively collected using postal questionnaires. RESULTS: Ten patients (mean age, 63 years; mean spherical equivalent, +4.7 D) had a median preoperative visual acuity of 0.20 that improved to 0.33 after surgery. Nine eyes showed visual improvement, three worsened, and two were unchanged. Histology showed disorganization of collagen fibrils, with amorphous deposits expanding the interfibrillary spaces. The mean thickness (+/-1 SD) of the excised scleral specimens was 585 +/- 309 microm, and the mean specific hydraulic conductivity was 23.9 +/- 27.5 x 10(-14) cm(2), compared with 5.8 +/- 3.9 x 10(-14) cm(2) in age-matched control specimens (P = 0.068). Three specimens had hydraulic conductivity above the 95% CI of the controls. Control eyes showed a significant reduction in diffusion coefficient (D) with age. Eyes had a mean D of 5.69 +/- 5.35 x 10(-8) cm(2) x s(-1), similar to control eyes (6.14 +/- 2.40 x 10(-8) cm(2) x s(-1), 20 kDa dextran). In one eye, the result was higher than the 95% CI of the control; in three, it was lower. CONCLUSIONS: UES is not caused by reduced scleral hydraulic conductivity, which tends to be higher than expected. Reduced macromolecular diffusion may impede the normal transscleral egress of albumin with subsequent osmotic fluid retention in some, but not all eyes.

Combined phacovitrectomy for macular hole: long-term results.

BACKGROUND AND OBJECTIVE: To present the long-term results of patients undergoing combined phacovitrectomy surgery for idiopathic macular hole at a single center. PATIENTS AND METHODS: A retrospective review of the records for 57 eyes of 53 consecutive patients who underwent combined phacovitrectomy for idiopathic macular hole during an 18-month period was completed at the Southampton Eye Unit. RESULTS: In 45 of 57 eyes (78.9%), the macular hole closed after one surgical procedure. Forty-seven patients had a follow-up period of more than 12 months (mean = 22.1 months). In this group, the mean visual acuity (standard deviation) improved by 0.37 (+/- 0.46) logarithm of the minimum angle of resolution units. Thirty-two (68%) cases had improved visual acuity of 2 or more Snellen lines. Hole closure rate at the final follow-up examination was 87.2%. CONCLUSION: Combining phacoemulsification and vitrectomy for an idiopathic macular hole has many benefits. It is a safe procedure and produces long-term results that are comparable to previously published series.

Late intraocular pressure rise following intravitreal triamcinolone injection.

Most ophthalmologists are aware of the risk of elevated intraocular pressure developing 1 or 2 months after an intravitreal injection of triamcinolone. However, the two cases reported here demonstrate that such a rise can occur significantly later than this. All patients who have had intravitreal steroid injection should therefore have prolonged intraocular pressure monitoring.

Reduced secretion of fibulin 5 in age-related macular degeneration and cutis laxa.

Age-related macular degeneration (ARMD) is the leading cause of irreversible visual loss in the Western world, affecting approximately 25 million people worldwide. The pathogenesis is complex and missense mutations in FBLN5 have been reported in association with ARMD. We have investigated the role of fibulin 5 in ARMD by completing the first European study of the gene FBLN5 in ARMD (using 2 European cohorts of 805 ARMD patients and 279 controls) and by determining the functional effects of the missense mutations on fibulin 5 expression. We also correlated the FBLN5 genotype with the ARMD phenotype. We found two novel sequence changes in ARMD patients that were absent in controls and expressed these and the other nine reported FBLN5 mutations associated with ARMD and two associated with the autosomal recessive disease cutis laxa. Fibulin 5 secretion was significantly reduced (P<0.001) for four ARMD (p.G412E, p.G267S, p.I169 T, and p.Q124P) and two cutis laxa (p.S227P, p.C217R) mutations. These results suggest that some missense mutations associated with ARMD lead to decreased fibulin 5 secretion with a possible corresponding reduction in elastinogenesis. This study confirms the previous work identifying an association between FBLN5 mutations and ARMD and for the first time suggests a functional mechanism by which these mutations can lead to ARMD. It further demonstrates that FBLN5 mutations can be associated with different phenotypes of ARMD (not limited to the previously described cuticular drusen type). Such knowledge may ultimately lead to the development of novel therapies for this common disease.