Medical Hypothesis, Discovery & Innovation (MEHDI) Ophthalmology Journal
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Hypo-angiogenesis: A possible pathological factor in the development of dry age-related macular degeneration and a novel therapeutic target
Get PDFBackground: Angiogenesis causes severe vision loss in patients with exudative or wet forms of age-related macular degeneration (AMD). The pathogenesis involves upregulation of several proangiogenic factors, particularly the vascular endothelial growth factor (VEGF). Contrary to the pathogenesis of exudative AMD, molecular events leading to the development of dry AMD remain unclear. Dry AMD is characterized by loss of the retinal pigment epithelium (RPE). The mechanism that triggers RPE cell loss remains unclear. Choriocapillaris development is absent in mice with RPE-specific deletion of VEGF. Moreover, in later life, background VEGF secretion promotes the survival of the RPE and maintains choriocapillaris integrity.
Hypothesis: We hypothesized that reduced synthesis of VEGF (hypo-angiogenesis) or abnormalities in its receptors, VEGF receptor-1 (VEGFR1) and VEGFR2, may be involved in the pathogenesis of non-exudative AMD or dry AMD. If the concept of hypo-angiogenesis as a driver for dry AMD is proven, treatment with VEGF or induction of angiogenesis could be considered. Similar attempts at therapeutic angiogenesis have been actively investigated in cardiac and limb ischemia.
Conclusions: The reasons for a patient developing exudative AMD or dry AMD remain poorly understood. Nevertheless, targeting increased VEGF production in patients with exudative AMD using anti-VEGF drugs is highly efficacious in preserving vision. Similarly, dry AMD may be a manifestation of reduced VEGF synthesis (hypo-angiogenesis) and subsequent decreased RPE cell survival. Experimental studies exploring the possibility of reduced VEGF secretion and/or increased receptor resistance/abnormality could pave the way for clinical trials of angiogenesis to treat dry AMD
Long-term outcomes of pars plana Ahmed valve implant and vitrectomy in eyes with refractory glaucoma
Get PDFBackground: Pars plana vitrectomy with implantation of an Ahmed glaucoma valve in the vitreous cavity has been reported with a success rate in the management of refractory and neovascular glaucoma. This study aimed to present the outcomes of pars plana Ahmed glaucoma valve (PPAV) surgical implantation in cases with refractory glaucoma.
Methods: In this single-center, retrospective, comparative study, 87 consecutive patients diagnosed with refractory glaucoma who underwent PPAV surgical implantation between October 2015 and October 2019 were evaluated. A successful postoperative outcome was defined as intraocular pressure (IOP) less than or equal to 21 mmHg upon examination and a reduction in the number of anti-glaucoma agents used at the last follow-up.
Results: Finally, 81 eyes of 78 patients with refractory glaucoma were included; 54 (66.66%) of the eyes had neovascular glaucoma. The mean follow-up was 20.65 ± 12.17 months (range: 2 to 52 months). The mean preoperative IOP was 40.01 ± 1.19 mmHg and reduced significantly to 16.73 ± 0.82 mmHg at the latest follow-up (P < 0.001); thus, a successful IOP outcome was achieved in 88.89% of eyes. The mean number of anti-glaucoma agents decreased significantly from 2.86 ± 0.09 preoperatively to 1.46 ± 0.11 at the latest follow-up (P < 0.001); while 61 (75.31%) of eyes had a reduction in the number of IOP lowering eye drops, and 14 (17.28%) had no need for IOP lowering eye drops.
Conclusions: PPAV surgery is a successful procedure for IOP reduction in patients with refractory glaucoma. Our study demonstrated either reduction or elimination of IOP lowering eye drops postoperatively. Large scale studies with a comparison group, a longer follow-up, and having various subtypes of glaucoma are required as future research to confirm these outcomes
Multi-color imaging in a unilateral central retinal artery occlusion following dengue fever: A case report and literature review
Get PDFBackground: Dengue fever is associated with various sight-threatening ocular manifestations, some of which can occur several months after fever. These include subconjunctival hemorrhage, vitreous hemorrhage, retinal hemorrhage, cotton wool spots, central and branch retinal artery occlusion, central scotoma, papilledema, optic neuropathy, retinal vasculitis, retinitis, retinal pigment epithelium mottling, foveolitis, choroidal effusion, exudative retinal detachment, anterior uveitis, endogenous endophthalmitis, and panophthalmitis. Herein, we report a patient with unilateral central retinal artery occlusion (CRAO) and raised dengue immunoglobulin G (IgG) titers who underwent serial multimodal imaging with fundus photography, spectral domain optical coherence tomography (SD-OCT), optical coherence tomography angiography (OCTA), and multi-color imaging (MCI). Furthermore, we reviewed recent publications highlighting different eye diseases and the role of MCI in their diagnosis and serial monitoring.
Case presentation: A 53-year-old Asian Indian woman complained of blurring of vision in the right eye (OD) two months after a bout of fever. Her best-corrected distance visual acuity was finger counting close to the face in the OD and 20/40 in the left eye. CRAO of the OD was diagnosed. Systemic investigations were normal except for elevated dengue IgG levels. Optical coherence tomography and fluorescein angiography confirmed this diagnosis. MCI and SD-OCT using Spectralis™ performed before and after treatment with oral steroids demonstrated improvement. MCI served as a noninvasive ancillary tool for monitoring the CRAO. In addition to the case report, we summarize articles pertaining to MCI published during the years 2018–2022. The list is not exhaustive but highlights salient features of different retinal and choroidal disorders evaluated using MCI. Our summary highlights the role of MCI in the diagnosis and serial monitoring of eye diseases.
Conclusions: A diagnosis of post-dengue fever retinal artery occlusion should be made after ruling out other causes of retinal artery vascular occlusion. We demonstrated retinal changes using serial imaging. MCI can be a useful tool, along with SD-OCT, to monitor clinical improvement. Optometrists can follow up patients with retinal vascular occlusions using noninvasive methods
Stay-at-home myopia among school children during the COVID-19 pandemic
Get PDFBackground: Uncorrected myopia represents a major cause of visual disability in children, especially in low-income and middle-income countries. However, there is still debate about the effect of e-learning and “stay-at-home” guidelines on the refractive status of school children, especially in the absence of long-term follow-up data. This study aimed to assess the impact of stay-at-home enforcement during the COVID-19 pandemic on myopia progression in students in the Suez Canal Area, Egypt.
Methods: This longitudinal observational study included 1650 students. All students aged 8–15 years with visual complaints, who had attended routine annual vision checks since 2018, were enrolled and assessed annually for myopia progression until 2021. Cycloplegic and noncycloplegic refraction, axial length (AL), corneal curvature, and uncorrected and best-corrected distance visual acuity were measured. The participants were administered a questionnaire that focused mainly on collecting information on their visual habits.
Results: Our study included 3300 eyes of 1650 school students with myopia during the 4-year study period from 2018 to 2021. The mean cycloplegic spherical equivalents (CSE) were - 1.02, - 1.52, - 2.00, and - 3.50 diopters (D) in 2018, 2019, 2020, and 2021, respectively. This myopic shift in CSE over time was significant (P < 0.001). The average keratometric reading (Avg K) increased significantly during the follow-up period (P < 0.001). The Avg K measurements were 42.32, 42.62, 43.02, and 44.19 D in 2018, 2019, 2020, and 2021, respectively. The changes in Avg K were significant (P < 0.001). The mean AL measurements were 22.53, 22.59, 22.69, and 22.71 mm in 2018, 2019, 2020, and 2021, respectively. Although statistically significant (P < 0.001), changes in AL were clinically insignificant throughout the study period. The mean durations spent on electronic devices at home were 2.12, 2.46, 3.10, and 6.00 hours in 2018, 2019, 2020, and 2021, respectively. The changes over time were significant (P < 0.001).
Conclusions: During the COVID-19 pandemic, studying at home accelerated the degree of refraction toward myopia in school children in Egypt. Further studies are needed to assess the academic performance of students with progressive myopia
Binocular vision parameters in handloom silk weavers
Get PDFBackground: Focusing the gaze for prolonged periods on a fixed distance demands high visual efficiency in handloom silk weavers and might result in various accommodative and vergence dysfunctions. The aim of the present study was to assess accommodative and vergence parameters and determine the frequency of non-strabismic binocular vision anomalies (NSBVAs) among handloom silk weavers.
Methods: In this cross-sectional study, we recruited voluntary handloom silk weavers from the Government-aided Society of Arignar Anna Silk Co-op Society K.H.-1, Kanchipuram, aged 20–39 years. All participants underwent preliminary visual examinations and comprehensive binocular vision testing of accommodative and vergence parameters. Sensory evaluation was performed using stereopsis testing and the Worth 4 Dot test. Motor evaluation included the ocular motility assessment, heterophoria checks for distance and near, near point of convergence, negative and positive fusional vergences for distance and near, vergence facility, negative and positive relative accommodations, both monocular and binocular near points of accommodation, and accommodative facility. The monocular estimate method was used to determine the accommodative response. Quantitative data are expressed as mean (standard deviation [SD]), and qualitative data are expressed as frequency (percentage).
Results: We recruited a total of 72 weavers, including 41 (56.9%) men and, 31 (43.1%) women with mean (SD) age, working hours, and work experience of 34.15 (4.12) years, 9 (2.5) h/day, and 17.5 (6.9) years, respectively. Of the 29 (40.3%) weavers with a refractive error, 18 (25%) had astigmatism; seven (9.7%) had myopia; and four (5.6%) had hyperopia. Of the 72 weavers, 38 (52.8%) presented with NSBVAs, including 13 (18.1%) with accommodative dysfunctions, 11 (15.3%) with vergence dysfunctions, and 14 (19.4%) with combined accommodative and vergence dysfunctions. Accommodative insufficiency was the most prevalent dysfunction among all NSBVAs. Overall, 57 (79.2%) handloom silk weavers reported vision-related symptoms during their weaving hours, all with NSBVAs (n = 38), 19 with normal parameters in the binocular vision test, and 15 with no symptoms.
Conclusions: The frequency of NSBVAs was high among handloom silk weavers compared to the literature. This implies a need for comprehensive binocular vision examination for people in this occupation to rule out NSBVAs for improving their quality of life and occupational productivity. Future large-scale studies are required to determine the exact NSBVAs prevalence among workers of this near vision-related occupation
Roles, responsibilities, and job description of ophthalmic nurses, a universal definition is required
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Chitosan-coated contact lens-based ophthalmic drug delivery system to manage Acanthamoeba keratitis: A preliminary hypothesis
Get PDFBackground: Acanthamoeba species can cause devastating contact lens (CL)-related microbial keratitis. Its culture is less sensitive, and little evidence is available for the safety or efficacy profile of medications. Therefore, early diagnosis and optimal treatment remain difficult. The aim of this study was to present the hypothesis that a novel chitosan-coated CL-based ophthalmic drug delivery system has therapeutic and prophylactic effects on acanthamoeba keratitis.
Hypothesis: CL-based drug delivery is a popular sustained-release drug delivery that extends the drug release time, thus increasing its bioavailability and treatment efficacy. Chitosan, a derivative of chitin, has antioxidant and broad-spectrum antimicrobial properties against fungi, yeasts, and bacteria. It acts against microbial cells; however, whether its mechanism of action is microbiostatic or microbicidal remains unknown. It exhibits wound healing and film-forming properties. Chitosan composite films permit high transmittance of visible light, making it transparent and therefore desirable for the development of CLs. Chitosan/Ag/ZnO blend films exhibit antimicrobial activities. Further, soft CLs coated with chitosan, sodium hyaluronate, polylysine hydrobromide, and sodium alginate show drug delivery properties and reduced bacterial growth. Recently, concentration-dependent anti-amoebic activities of chitosan and nano-chitosan against the trophozoite and cystic forms of Acanthamoeba have been reported. Based on the existing evidence, we hypothesized that a chitosan-coated CL-based ophthalmic drug delivery system could have therapeutic and prophylactic effects on acanthamoeba keratitis or subsequent endophthalmitis.
Conclusions: CLs or intraocular implants with chitosan-based nanocoatings alone or in combination with routine treatment may be preventive or therapeutic for acanthamoeba keratitis or endophthalmitis. Experimental studies and further clinical trials are required to explore the efficacy and safety profile. Moreover, randomized controlled trials in healthy eyes with soft or hard CLs or orthokeratology lenses for refractive error correction may shed light on the prophylactic effect of this novel drug delivery system. Other forms of ophthalmic drug delivery systems using chitosan-based nanocoatings should be studied additionally
Blue light-blocking efficiency of blue light-blocking and driving spectacle lenses
Get PDFBackground: Retinal damage caused by blue light can result in glare, decreased visual acuity, and accelerated macular degeneration. In clinical practice, blue light-blocking glasses, such as driving glasses, are used to block blue light effectively. This study was aimed at measuring light transmittance to analyze the blue light-blocking efficiencies of blue light-blocking and driving spectacle lenses manufactured with tinting, coating, and only materials and at distinguishing the difference between the two spectacle lenses.
Methods: Blue light-blocking and driving spectacle lenses used to measure light transmittance were manufactured with tinting (blue light blocking lenses by tinting or “BTL” and driving spectacle lenses by tinting or “DTL,” respectively), coating (blue light blocking lenses by coating or “BCL” and driving spectacle lenses by coating or “DCL,” respectively), and only materials (blue light blocking lenses by material or “BML” and driving spectacle lenses by material or “DML,” respectively).
Results: Compared to BTL, DTL had a significantly greater decrease in the light transmission efficiency for visible and blue lights (P < 0.05). The blue light hazard function was lower for BML and DML than for conventional coating lenses in both visible and blue lights, although without significant differences between visible and blue lights (P > 0.05).
Conclusions: The blue light-blocking spectacle lenses had the highest blue light-blocking efficiency when manufactured with tinting, coating, and only materials, in order. With DML, the blue light-blocking efficiency was lower compared to DTL but higher compared to DCL. Therefore, DML could provide a balanced glare control and clear retinal image overall
Combined umbilical cord patching with amniotic membrane graft for corneal surface reconstruction
Get PDFBackground: Umbilical cord patch (UCP) grafts have been successfully used for glaucoma shunt tube coverage and conjunctival surface reconstruction. In recent years, the technique has emerged as a novel alternative for the reconstruction of corneal perforation and descemetocele. This study aimed to evaluate the effectiveness of combined UCP grafting and human amniotic membrane (HAM) transplantation for the management of corneal perforation or descemetocele.
Methods: This prospective, non-comparative, interventional case series included nine eyes of nine patients with corneal descemetoceles and 28 eyes of 28 patients with corneal perforations, all in a clinically quiescent state. UCP grafting and HAM transplantation were combined to treat all patients. We re-examined the patients daily throughout the first week, weekly for 1 month, and then monthly for the first 6 months using slit-lamp examination and anterior segment optical coherence tomography.
Results: We included 37 eyes with descemetocele or corneal perforation in a clinically quiescent state. The mean (standard deviation) ages of patients with corneal descemetocele and corneal perforation were 56.3 (18.8) years and 54.3 (18.1) years, respectively. The male-to-female ratios in patients with corneal descemetocele and corneal perforation were 56% to 44% and 61% to 39%, respectively. Postoperative corneal thickness increased significantly in eyes with descemetocele compared to preoperative values (P < 0.001). Postoperative best-corrected distance visual acuity improved significantly compared to preoperative values in eyes with descemetocele or corneal perforation (both P < 0.001), with relief of accompanying ocular symptoms. We did not observe any recurrence or complications such as rejection, infection, suture-related problems, or severe inflammation and all had a formed anterior chamber up to the final follow-up visit.
Conclusions: Combined UCP grafting and HAM transplantation could be a promising alternative treatment for corneal perforation or descemetocele in clinically quiescent eyes, providing satisfactory reconstruction and functional outcomes. Further studies with robust designs, larger sample sizes, and longer follow-up are needed to verify the efficacy and safety of this modified surgical technique in enhancing vision and restoring anterior segment anatomical integrity in compromised corneas
Add-on therapy with different non-steroidal anti-inflammatory agents in the management of non-infectious, non-necrotizing episcleritis
Get PDFBackground: Episcleritis is a common ocular inflammatory disease that can cause red eye. It is usually managed using single or combined topical corticosteroids and topical or oral non-steroidal anti-inflammatory drugs (NSAIDs) as directed by clinical response. However, recurrence is possible. This study aimed to compare the effects of add-on therapies using different topical NSAIDs in the management of treatment-naive, non-infectious, non-necrotizing episcleritis.
Methods: Seventy-five eyes of 75 patients with non-infectious, non-necrotizing unilateral episcleritis were included in this study. Patients were allocated to one of three groups based on the NSAID used as add-on therapy: topical diclofenac sodium 0.1% (group D), topical nepafenac 0.1% (group N1), and topical nepafenac 0.3% (group N3). The time to symptom disappearance was defined as the recovery time.
Results: There were no statistically significant differences in age, sex, initial best-corrected distance visual acuity, and intraocular pressure between groups (all P > 0.05). The mean recovery times of groups D and N1 were comparable (12.86 ± 5.35 days and 11.45 ± 5.42 days, respectively) (P > 0.05). However, the mean recovery time of group N3 was significantly shorter (9.70 ± 3.80 days, P < 0.05). Recurrence was observed in only one patient in group N1 at 3 months, and symptoms resolved when the same medication was reinstituted. Furthermore, we noted no side effects during the follow-up period for any of the treatment modalities.
Conclusions: All three topical NSAIDs were effective add-on therapies in the management of non-infectious, non-necrotizing unilateral episcleritis. However, once-daily administration of topical nepafenac 0.3% had a shorter recovery time than topical diclofenac 0.1% and topical nepafenac 0.1%