Pathophysiology of Age-Related Macular Degeneration: Implications for Treatment.

Age-related macular degeneration (AMD) is a complex, multifactorial, progressive retinal disease that affects millions of people worldwide and has become the leading cause of visual impairment in developed countries. The disease etiopathogenesis is not understood fully, although many triggers and processes that lead to dysfunction and degeneration of the retinal pigment epithelium (RPE) have already been identified. Thus, the lack of cellular control of oxidative stress, altered proteostasis, dysfunction of lipid homeostasis, and mitochondrial dysfunction form an internal feedback loop that causes the RPE to fail and allows accumulation of abnormal misfolded proteins and abnormal lipids that will form drusen. An inadequate antioxidant response, deficits in autophagy mechanisms, and dysregulation of the extracellular matrix (ECM) help to increase the deposition of abnormal drusen material over time. The drusen then act as inflammatory centers that trigger chronic inflammation of the subretinal space in which microglia and recruited macrophages are also involved, and where the complement system is a key component. Choriocapillaris degeneration and nutritional influences are also classic elements recognized in the AMD pathophysiology. The genetic component of the disease is embodied in the recognition of the described risk or protective polymorphisms of some complement and ECM related genes (mainly CFH and ARMS2/HTRA1). Thus, carriers of the risk haplotype at ARMS2/HTRA1 have a higher risk of developing late AMD at a younger age. Finally, gut microbiota and epigenetics may play a role in modulating the progression to advanced AMD with the presence of local inflammatory conditions. Because of multiple implicated processes, different complex combinations of treatments will probably be the best option to obtain the best visual results; they in turn will differ depending on the type and spectrum of disease affecting individual patients or the disease stage in each patient at a specific moment. This will undoubtedly lead to personalized medicine for control and hopefully find a future cure. This necessitates the continued unraveling of all the processes involved in the pathogenesis of AMD that must be understood to devise the combinations of treatments for different concurrent or subsequent problems.

A new manual retinal thickness measurement protocol to evaluate high myopia patients.

PURPOSE: To validate a manual measurement protocol for quantifying retinal thickness (RT) using an optical coherence tomography (OCT) device in pathologic myopia patients. METHODS: The macular Cross Hair protocol of Stratus OCT3 (Carl Zeiss Meditec, Inc., Dublin, Calif., USA) was applied and manual RT gauging was performed using the caliper tool. Foveal and paramacular RT, located at 1 and 2 mm distances from the fovea in both vertical and horizontal scans, were measured. Three consecutive RT measurements were taken to assess measurement reliability. The within-subject coefficient of variation (CVw) and intraclass correlation coefficients (ICC) were calculated to validate the manual method. RESULTS: The mean axial length of the 29 eyes assessed was 28.28 ± 2.72 mm and the mean spherical refraction was -13.61 ± 6.68 diopters. CVw ranged from 0.86 to 8.73% and ICC varied from 0.81 to 0.98. CONCLUSION: A manual RT measurement protocol could reliably be used in the daily clinic for assessing pathologic myopic patients when OCT software segmentation fails.

Ocular pain after intravitreal injection.

PURPOSE: To evaluate the efficacy of different anesthetics and topical anti-inflammatory treatment in patients undergoing intravitreal injections (IVI). METHODS: Prospective, randomized, double masked, comparative study. Patients undergoing 0.05 mL IVI were randomized to two different preoperative anesthetic regimes (regime A [0.5% tetracaine + naphazoline] versus regime B [5% lidocaine]) and two different post-injection topical protocols (protocol 1 [tobramycin qid] versus protocol 2 [tobramycin qid + diclofenac qid]). Patients were trained to score pain using a numerical rating pain scale from 0 (no pain) to 10 (excruciating pain) immediately after the injection, 30 min and 24 h later. Patients were instructed to take oral paracetamol (650-1000 mg, adjusted to the patient's weight) every six hours ad lib if necessary. RESULTS: A total of 156 patients were enrolled; 86 patients were randomized to regime A and 70 to regime B; 78 patients were assigned to each of the post-injection topical protocols. The average pain score immediately after the IVI was 2.77 (SD 2.12) for the whole group (2.85, SD 2.23 with tetracaine and 2.67, SD 2.00 with lidocaine; p = 0.73, Mann-Whitney U-test). Twenty-four hours later, the average pain score was 1.84, SD 2.45 (topical diclofenac + tobramycin) versus 1.75, SD 1.83 (topical tobramycin; p = 0.46, Mann-Whitney U-test). Forty-seven patients (30%) required oral paracetamol (average 3.3 and range 1-5 tablets). Conjunctival hemorrhage 30 min after the injection was less frequent and severe in eyes treated with topical naphazoline (p = 0.055, Mann-Whitney U-test). CONCLUSIONS: Topical tetracaine and lidocaine provide similar anesthesia before IVI. Topical diclofenac does not seem to reduce pain scores after IVI.

Ocular toxicity caused by toad venom.

PURPOSE: To report a case of ocular toxicity caused by toad venom. METHODS: Observational case report. RESULTS: A 31-year-old man came to our clinic complaining of burning pain, photophobia, and blurred vision in both eyes. He reported that an hour earlier he had been handling a toad (Bufo bufo). It ejected a liquid from its back that splashed on the patient's face and made him rub his eyes. Corrected visual acuity was 20/50 in the right eye and 20/40 in the left eye. Slit-lamp microscopy revealed mild chemosis and stromal corneal edema with Descemet folds in both eyes. Intraocular pressure (IOP) was 9 mm Hg in both eyes. Posterior segment examination was normal. Topical dexamethasone every 4 hours and cycloplegic 3 times a day were prescribed. Forty-eight hours later, corneal edema and conjunctival chemosis had resolved, and IOP was 18 mm Hg. CONCLUSIONS: Ocular toxicity secondary to toad venom may cause corneal edema and low IOP that resolve without specific treatment in a short period.