Medical hypothesis discovery and innovation in ophthalmology

Safety and efficacy of implantable phakic contact lens versus implantable collamer lens in myopia correction

Ibrahim Amer — 2024-01-31

Background: Phakic intraocular lenses (pIOLs) have proven to be excellent substitutes for excimer laser keratorefractive surgery in certain situations. We aimed to assess the efficacy and safety of two pIOLs, the implantable collamer lens (ICL V4c) versus the implantable phakic contact lens (IPCL V2), for myopic correction.

Methods: In this prospective randomized clinical trial, we allocated eligible eyes with myopia > - 6 diopters into IPCL or ICL implantation groups, each including 100 eyes of 100 individuals. Preoperative and postoperative assessments at 3, 6, and 12 months included measurements of the spherical equivalent (SE), uncorrected distance visual acuity (UCDVA), best-corrected distance visual acuity (BCDVA), intraocular pressure (IOP), maximum keratometry (K1), minimum keratometry (K2), mean keratometry (Kmean), anterior chamber depth (ACD), anterior chamber angle (ACA), and endothelial cell density (ECD).

Results: The groups had comparable demographic characteristics and baseline visual and anatomical values (all P > 0.05). The UCDVA, BCDVA, and SE of the two groups were comparable at baseline and at all postoperative follow-up examinations (all P > 0.05). Both groups experienced significant improvements in UCDVA, BCDVA, and SE at three months postoperatively (all P = 0.001), and measurements remained stable for up to 12 months. Keratometry readings were comparable between the groups over the follow-up period and remained unchanged at all visits (all P > 0.05). The ACA in the ICL group was significantly decreased at three months postoperatively (P = 0.001) and then widened significantly at 6 and 12 months (both P = 0.001). In the IPCL group, the postoperative ACA was significantly decreased at three months (P = 0.001) and was comparable to that in the ICL group (P > 0.01). However, at the 6- and 12-month postoperative visits, the ACA was significantly narrower in the IPCL group than in the ICL group (both P = 0.001). The ACD in both groups was decreased at three months postoperatively (both P = 0.001) and remained stable until the end of the study. The ECD remained comparable between the groups at all postoperative visits (all P > 0.05). We did not observe a significant ECD reduction in either group at any postoperative follow-up visit (all P > 0.05). We encountered no serious complications in either group.

Conclusions: ICL and IPCL had comparable safety and efficacy outcomes in terms of anterior chamber morphometrics, visual and refractive results, and corneal parameters. Further multicenter randomized clinical trials with longer follow-up periods, larger sample sizes, and measurement of additional anterior chamber and corneal morphometrics, vault, and other vision parameters are needed to verify these findings.

Non-penetrating deep sclerectomy versus combined trabeculotomy–trabeculectomy in primary congenital glaucoma

Ibrahim Hassan Elabd — 2024-01-31

Background: The primary mode of therapy in children with primary congenital glaucoma (PCG) and mild or no corneal edema is goniotomy, which has a high success rate. However, in developing countries, the diagnosis of PCG is usually delayed, and corneal cloudiness interferes with goniotomy. Therefore, trabeculotomy may be the best choice in such eyes. We compared the short-term efficacy and safety of primary combined trabeculotomy–trabeculectomy (primary CTT) with that of non-penetrating deep sclerectomy (NPDS) in managing PCG.

Methods: This prospective, randomized, comparative study included patients with PCG referred to Al-Azhar University Hospitals within a 1-year period. Eyes were randomly allocated to one of two groups: eyes in NPDS group underwent NPDS, and those in primary CTT group underwent primary CTT. Baseline and frequent postoperative assessments of intraocular pressure (IOP), cup-to-disc ratio (C/D ratio), corneal diameter, and axial length were performed for up to 6 months. The success rates were recorded in both groups.

Results: Forty eyes of 26 patients were included, with 20 eyes allocated to each group. The mean (standard deviation) age of all patients was 12.9 (9.5) months, with comparable ages and sex ratios between groups (both P > 0.05). Both groups demonstrated a significant reduction in IOP and C/D ratio at each postoperative visit compared to the baseline visit (all P < 0.001), with no significant difference detected between the groups (all P > 0.05), except for a significantly lower IOP in NPDS group at 1 month (P < 0.05). The corneal diameter and axial length were comparable between groups at baseline and remained unchanged at all postoperative visits (all P > 0.05). The groups had comparable success rates (P > 0.05). No serious complications were detected.

Conclusions: CTT and NPDS both yielded reasonable IOP control and reversal of cupping in eyes with PCG. We observed equal effectiveness of the surgical procedures without major safety concerns. Further large-scale clinical trials with longer follow-up periods are needed to verify our preliminary findings.

Ocular surface lesions in clinical grades of Bell’s phenomenon

Omer Faruk Yilmaz — 2024-01-31

Background: Bell’s phenomenon, also known as the palpebral oculogyric reflex, is a critical reflex that protects the cornea. We developed an innovative, simple, and practical grading scale for Bell’s phenomenon that includes the inverse Bell’s phenomenon. Using this scale, we investigated the characteristics of Bell’s phenomenon among asymptomatic individuals in different age groups and examined the frequency of ocular surface lesions in asymptomatic and symptomatic participants with different grades.

Methods: Bell’s phenomenon was classified into five grades: grade +2 (strong positive), grade +1 (weak positive), grade 0 (no Bell’s phenomenon, no eye movement), grade –1 (weak inverse), and grade –2 (strong inverse). In this cross-sectional study, we randomly included 330 eyes of 165 asymptomatic, healthy, White Turkish individuals who attended the outpatient eye clinic, with a male-to-female ratio of 1:1.4, in the control group. These were categorized into four age groups: 4 – 20 years, 21 – 40 years, 41 – 60 years, and > 60 years. Eighty eyes from 40 patients with ocular surface lesions and absence of grade +2 Bell’s phenomenon were included in the symptomatic group.

Results: We detected higher frequencies of grade +2, +1, and 0 in individuals aged 4 – 40, 41 – 60, and > 60 years, respectively. There was a significant difference between age groups in the frequencies of different grades (P < 0.001). Pairwise analysis revealed a significantly lower frequency of grade +2 in the age group > 60 years compared with the 4 – 20 and 21 – 40 year groups (both P < 0.05). Grade +2 was the most frequent in both sexes. We detected grade 0 in 27.1% of men and 22.1% of women in the control group, with no significant difference in the frequencies of different grades between sexes (P > 0.05). We observed significant differences between grades with respect to the frequency of ocular surface lesions (P < 0.001). Pairwise analysis revealed a significantly higher frequency of ocular surface lesions in asymptomatic individuals with grade 0 and all four other grades (all P < 0.001). However, the frequency of ocular surface lesions was comparable between sexes (P > 0.05). Of the 40 symptomatic individuals, 28 (70%), 5 (12.5%), 4 (10%), and 3 (7.5%) had grade 0, +1, –1, and –2, respectively. The number of symptomatic patients was higher in grade 0 (n = 28) than in other grades (grade +1, –1, and –2: n = 12 patients), and these individuals had a higher frequency of ocular surface lesions (n = 38 lesions) than others (grade +1, –1, and –2: 7 lesions).

Conclusions: Using a simple, practical grading scale for Bell’s phenomenon that includes inverse Bell’s phenomenon, we observed that inverse Bell’s phenomenon is a reflex that may be present in healthy individuals and could have a protective effect on the eye, although not to such a degree as a strong Bell’s phenomenon. Our observations imply that bilateral conjunctival calcifications/Vogt’s limbal girdle may be associated with grades 0 and +1 Bell’s phenomenon. Further large-scale studies are needed to determine the frequency of Bell’s phenomenon in the general population using this innovative, simple, practical grading scale, and to identify the protective or injurious effect of each grade on the ocular surface.

Optical coherence tomography in multiple sclerosis

Amin Najafi — 2024-01-31

Background: Multiple sclerosis (MS) is a chronic neurodegenerative disease that damages myelinated fibers within the central nervous system. Data obtained using optical coherence tomography (OCT) have recently been identified as a potential biomarker for this disease. We aimed to measure circumpapillary retinal nerve fiber layer thickness (cpRNFLT) using OCT and to compare the results in healthy participants with those of individuals having clinically definitive MS with and without a history of optic neuritis.

Methods: This cross-sectional study recruited patients with clinically confirmed MS, with and without optic neuritis, and healthy individuals as a control group. We documented demographic characteristics, duration of MS, and time elapsed since the episode of optic neuritis. All participants underwent a thorough ocular examination and measurement of total, superior, and inferior cpRNFLT using swept-source OCT.

Results: In participants with MS, women outnumbered men in the subsets with (90%) and without (64%) optic neuritis. The control group comprised approximately similar numbers of men and women. There was a statistically significant difference in total, superior, and inferior cpRNFLT between study groups (all P < 0.001). Pairwise comparisons revealed significantly thinner total, superior, and inferior cpRNFLTs in patients having MS with and without (all P < 0.001) optic neuritis when compared with the controls. We found significantly higher total, superior, and inferior cpRNFLTs in women than in men (all P < 0.05). However, we found no significant correlation between total, superior, or inferior cpRNFLT and patient age, duration of MS, or time elapsed since the optic neuritis episode (all P > 0.05), except for a significant moderate inverse correlation between patient age and total cpRNFLT (r = - 0.41; P < 0.05), indicating a loss of total cpRNFLT with age.

Conclusions: Patients with clinically confirmed MS, with or without optic neuritis, had a significantly decreased cpRNFLT compared to that of healthy individuals. There was a significant inverse correlation between age and total cpRNFLT and a difference in cpRNFLT between the sexes, indicating that age and sex may influence the measurement of cpRNFLT using OCT in patients with MS. As a screening tool, OCT should be used along with other existing diagnostic modalities for patients with definite or suspected MS. Further longitudinal studies including various classifications of MS with or without isolated episodes of optic neuritis, along with diagnostic accuracy studies, could provide more robust conclusions on the suitability of OCT as a biomarker of MS.

Ocular injuries sustained at home in five metropolitan cities: a review of 5008 cases

Meisam Sharifi — 2024-01-31

Background: In Iran, ocular injuries sustained at home are a growing public health issue, and few studies have explored their prevalence and the frequencies of different causes of these injuries. We investigated the features of ocular injuries at home among children and adolescents (aged < 18 years), adults (18 – 64 years), and the elderly (greater than or equal to 65 years) in five metropolitan cities.

Methods: In this cross-sectional study, we recruited individuals with ocular injuries sustained at home who presented to 12 public/teaching hospitals in five metropolitan cities during a 5-month period. Using clinical records within the emergency department archives, we collected the following data: age, sex, frequency of injuries requiring hospital admission or surgical intervention, and causes of eye injuries, documented as 1) cleaning products, 2) chemical products, 3) kitchen items, 4) cooking activities, 5) toys, 6) falls from height, 7) sports equipment, 8) penetrating or cutting, 9) abrasions, 10) foreign bodies, and 11) direct blows by other individuals.

Results: Of 5008 participants from the five cities, 74% (n = 3711) were male and 26% (n = 1297) were female. The most frequent causes of injury among children and adolescents, adults, and the elderly were toys, kitchen items, and cooking activities, respectively. In children and adolescents, injuries were caused by kitchen items, toys, foreign bodies, and direct blows by other individuals more frequently than in adults or the elderly, and by cleaning products and abrasions more frequently than in the elderly (all P < 0.05). In adults, injuries were caused by cleaning products, cooking activities, falls from height, sports equipment, penetrating or cutting, and abrasions more frequently than in children and adolescents or the elderly (all P < 0.05), and by kitchen items, toys, and blows by other individuals more frequently than in the elderly (all P < 0.05). In the elderly, injuries were caused by chemical products more frequently than in children and adolescents or adults, and by cooking activities, falls from height, and sports equipment more frequently than in children and adolescents (all P < 0.05). In adults, the frequency of ocular injuries was significantly higher in Tehran and lower in Mashhad when comparing each with that of the other four cities (all P < 0.05). We found a significantly higher frequency of ocular injuries by cleaning and chemical products in Tehran, by toys in Shiraz, by falls from height in Isfahan, and by direct blows by other individuals in Ahvaz when comparing each to that of the other four cities (all P < 0.05). Regarding the prevalence of severe ocular injuries among the children/adolescent and adult age groups, conditions were relatively better in Shiraz and relatively unfavorable in Mashhad.

Conclusions: Ocular trauma was more common in male individuals and the younger age groups. Approximately half of the causes were kitchen items, toys, and foreign bodies, which are avoidable by enhancing public eye health awareness. The prevalence of severe ocular injuries in individuals aged < 18 years was high, highlighting the necessity of nationwide preventive strategies for pediatric ocular injuries.

Pseudovitelliform maculopathy associated with hereditary hemochromatosis

Ante Vukojevic — 2024-01-31

Background: Hereditary hemochromatosis (HH) is an inherited autosomal recessive iron metabolism disorder resulting from a C282Y mutation in the HFE gene. Mutations in the HFE gene may result in iron accumulation and oxidative stress in the retina, resulting in macular degeneration. This article describes two patients with HH who were treated with erythrocytapheresis or phlebotomy, with no exposure to deferoxamine or any other chelation therapy, and who developed visual symptoms.

Case Presentation: Both patients had known diagnoses of HH. Because of visual symptoms, they were referred to the ophthalmology clinic and underwent a retinal exam, multimodal imaging, and electrodiagnostic studies, which revealed structural and functional degeneration of the central macula. Fundus photography, fluorescein angiography, and fundus autofluorescence revealed changes at the level of the retinal pigment epithelium (RPE) in the central macula. In addition, optical coherence tomography revealed subfoveal accumulation of hyperreflective material at and below the RPE. Multifocal electroretinography confirmed a decreased cone response, whereas the full-field electroretinogram was unremarkable. Genetic testing ruled out Best’s vitelliform macular dystrophy and the other known hereditary macular dystrophies. The patients had known diagnoses of HH, homozygous C282Y mutations in the HFE gene, and no comorbidities; thus, we presumed that HH led to the observed morphological and functional disorders of the RPE, which in turn caused structural macular changes in both patients.

Conclusions: Considering the macular findings and the nature of the patients’ primary illness, we believe that the accumulation of iron and photoreceptor metabolic products caused dysfunction in the RPE, which led to morphological and functional changes in the macula. Because the patients were not treated using chelating agents, we attribute the macular changes solely to iron accumulation and oxidative stress caused by the pathophysiological processes of HH. Further studies are needed to identify the plausible molecular or cellular insults underlying pseudovitelliform macular degeneration in patients with HH.

COVID-19 and children’s eyes

Nima Rastegar Rad — 2024-01-31

Letter