Medical Hypothesis, Discovery & Innovation (MEHDI) Ophthalmology Journal
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Anterior segment parameters after trabeculectomy in pseudoexfoliation glaucoma versus primary open-angle glaucoma
Full text linkBackground: The effects of trabeculectomy on anterior segment parameters have been widely investigated. However, the stabilization time for various glaucoma types after trabeculectomy remains debatable. We investigated the effect of mitomycin C-augmented trabeculectomy on ocular anterior segment parameters in primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) during short-term follow-up using the Pentacam HR.
Methods: In this retrospective observational study, consecutive patients diagnosed with medically uncontrolled POAG or PXG who underwent MMC-augmented trabeculectomy were recruited. All individuals underwent detailed ocular examinations. All trabeculectomies were performed by a single surgeon using the same technique. Anterior segment parameters, including anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured using the Pentacam HR, along with intraocular pressure (IOP) using a Goldmann applanation tonometer, pre-operatively and at 1-week, 1-month, and 3-month post-operative visits.
Results: We included 80 patients with a median (range) age of 58.0 (41.0–86.0) years having a nearly similar sex ratio. The study groups were matched according to sex and age (both P > 0.05). The group-by-time interaction was significant for CCT and ACV (both P < 0.05) but not for IOP, ACD, and ACA (all P > 0.05). The mean (standard deviation [SD]) IOP, ACD, and ACA were comparable between groups (all P > 0.05) during the 3-month period; however, they changed significantly over time in both groups (all P < 0.001). The mean CCT and ACV were comparable between groups at each time point (all P > 0.05), except at the 1-month post-operative visit, at which the mean (SD) ACV was significantly lower in the PXG group (P < 0.05). We found a comparable mean (SD) CCT between paired visits in each group (all P > 0.05), except for the mean (SD) CCT at 3 months, which was significantly lower than that at the 1-month post-operative visit in the PXG group (P < 0.05). We found a comparable mean (SD) ACV between paired visits in each group (all P > 0.05); however, it was significantly lower at the 1-month post-operative versus the baseline visit in both groups and resumed a significantly higher value at the 1-month versus the 1-week visit and at the 3-month versus the 1-month visit in the PXG group (all P < 0.05).
Conclusions: We observed significant changes in IOP, ACD, and ACA over 3 months after post-augmented trabeculectomy in eyes with POAG and PXG; however, the majority of anterior segment parameters were comparable between the two groups. Further large-scale studies with longer follow-up periods should be conducted to verify the post-operative fluctuations in these parameters in POAG and PXG
Cataract surgery in retinitis pigmentosa
Full text linkBackground: Retinitis pigmentosa (RP) is an inherited retinal dystrophy characterized by progressive vision loss due to photoreceptor degeneration. Complicated cataract formation, particularly posterior subcapsular cataract (PSC), frequently occurs in RP and exacerbates the visual impairment. Cataract surgery may improve vision; however, the distinctive challenges of RP require specific considerations. This mini-review aims to provide a comprehensive overview of the RP-related cataract.
Methods: A comprehensive literature review was conducted via PubMed/MEDLINE, spanning the period from January 1976 to June 2024, using the keywords “cataract,” “cataract surgery,” “cystoid macular edema,” “hereditary retinal dystrophy,” “retinitis pigmentosa,” “posterior subcapsular cataract,” “posterior capsular opacification,” “zonular weakness,” and “artificial intelligence.” We aimed to evaluate cataract surgery in patients with RP, focusing on cataract formation, its surgical management, postoperative complications, patient follow-up, and visual outcomes. Relevant review articles, clinical trials, and case reports with related reference lists of these articles were included.
Results: A total of 53 articles were examined in detail, including those identified through focused keyword searches and the reference lists of these articles. Cataract surgery in patients with RP generally results in substantial visual improvement. However, surgery can be complicated, particularly by zonular weakness and subluxation of the crystalline lens. These risks can be reduced by using capsular tension rings and employing meticulous surgical technique. Furthermore, postoperative complications, such as cystoid macular edema and posterior capsular opacification, are common. Despite these challenges, regular postoperative follow-up and appropriate management can help mitigate complications. Integrity of the ellipsoid zone and external limiting membrane on preoperative optical coherence tomographic examination are the main predictors of visual outcomes following cataract surgery; however, outcomes can vary. Though many patients experience significant visual improvement, some may experience limited benefits due to pre-existing advanced retinal degeneration.
Conclusions: Cataract surgery may offer meaningful visual benefits in patients with RP; however, careful preoperative evaluation and meticulous surgical technique are required to address the possible challenges. Attentive postoperative care and follow-up are essential to optimize visual outcomes. Early surgical intervention can significantly improve the quality of life in selected candidates, and tailored approaches are necessary in patients with RP requiring cataract surgery. Further studies on the potential application of artificial intelligence to monitor postoperative recovery and detect complications may improve surgical outcomes and enhance patient care
Contrast sensitivity assessment using the Mars letter contrast sensitivity test
Full text linkBackground: Contrast sensitivity (CS) represents an individual’s ability to detect differences in luminance between two areas and is an essential component of vision. Various studies have evaluated the relevance of different charts to assess CS in ophthalmology practice. We evaluated the CS of healthy individuals using the Mars letter CS chart.
Methods: In this hospital-based cross-sectional study, we consecutively recruited healthy individuals older than 18 years with unremarkable ocular examinations who attended the general outpatient clinic at Benue State University Teaching Hospital, Makurdi, Nigeria, between March 2021 and July 2021. Each participant was allocated to one of five groups with 10-year age intervals and 1:1 male-to-female ratios. All participants underwent a detailed ophthalmic examination. We tested visual fields using the 24-2 program on a Humphrey visual field analyzer with appropriate refractive correction. Monocular testing of CS with appropriate spectacle correction was performed using a Mars letter CS chart. The tribe, age, and sex of each individual, along with the best-corrected visual acuity (BCVA), intraocular pressure, mesopic pupil size, cup-to-disc ratio (C/D ratio), and mean deviation (MD) of the visual field for each eye were recorded.
Results: A total of 100 eyes of 50 patients with a mean (standard deviation [SD]) age of 44.6 (12.8) years and a 1:1 male-to-female ratio were enrolled. The mean (SD) CS score for the 100 included eyes was 1.67 (0.09) log units. The mean (SD) CS score was comparable between sex groups and tribes (both P > 0.05) yet differed significantly between age groups (P < 0.001). We found a significant good inverse correlation between CS score and age (r = - 0.60; P = 0.001), a low inverse correlation with BCVA (r = - 0.29; P < 0.003), and a low direct correlation with C/D ratio (r = + 0.23; P = 0.023); however, we observed no significant correlation with tribe (r = + 0.07; P = 0.053), sex (r = + 0.16; P = 0.123), IOP (r = + 0.07; P = 0.481), mesopic pupil size (r = - 0.02; P = 0.861), and mean deviation of visual field (r = + 0.02; P = 0.873).
Conclusions: We observed a progressive decline in the mean CS score in healthy eyes with each decade of increase in age. Our findings are similar to those of previous studies and could be used as reference values for the healthy population among various age groups. However, further studies with larger sample sizes are necessary to encourage clinicians to incorporate CS into routine examinations. Further studies must compare these normative values with those of disease conditions to further understand the clinical application of the CS test
Non-penetrating deep sclerectomy versus combined trabeculotomy–trabeculectomy in primary congenital glaucoma
Full text linkBackground: 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
Retinal changes in preeclampsia
Full text linkBackground: The eye undergoes a series of physiological changes during pregnancy in response to metabolic and hormonal adaptation. Preeclampsia (PE) is the main cause of maternal morbidity and is associated with serious pregnancy-related complications. Characterized by hypertension and proteinuria, PE affects 2–8% of pregnancies globally. Previous studies have indicated that PE compromises retinal health. We examined the effects of PE on retinal structure and vasculature.
Methods: We conducted a literature review by searching PubMed/MEDLINE, Embase, and Scopus using terms pertaining to PE and the retina. The review included articles published between January 1, 1990, and May 30, 2024. The articles were selected based on their relevance to the topic. The key findings are summarized to offer a comprehensive overview of current knowledge, highlight the pathophysiology and manifestations of PE-related retinal changes, and propose clinical implications, diagnostic clues, and management strategies.
Results: PE is associated with visual disturbances caused by various retinal changes, including arteriolar narrowing, vasospasm, hemorrhages, exudates, serous retinal detachment, macular edema, retinal vein occlusion, and choroidal ischemia. These are mostly evident on fundus examination and frequently resolve postpartum. The underlying pathophysiology involves endothelial dysfunction, hypertension, inflammation, and coagulopathy. These retinal changes have immediate clinical implications and long-term risks, necessitating early detection, prompt multidisciplinary management, and close follow-up. Although most PE-associated retinal disturbances spontaneously resolve after the termination of pregnancy, one-third of patients are likely to experience long-lasting consequences
Conclusions: Visual disturbances may precede and portend the onset of PE. Early detection and prompt management will mitigate fetal and maternal morbidity and mortality. Understanding the underlying pathophysiology of PE-related retinal manifestations is crucial for optimal management, because the majority of manifestations are reversible. Although retinal changes secondary to PE typically resolves postpartum, some studies demonstrated that women with PE may have a higher long-standing risk of ocular disorders. A multidisciplinary team approach involving obstetricians, ophthalmologists, and healthcare providers is essential for the immediate and long-term management of ocular consequences in pregnancy. Consequently, additional studies associated with robust methodologies are required to develop clinical guidelines
Corneal densitometry changes after femtosecond laser-assisted intracorneal ring segments implantation in keratoconus
Full text linkBackground: Intrastromal corneal ring segments are commonly implanted in the corneas of eyes with mild-to-moderate keratoconus; however, changes in corneal densitometry (CD) after implantation are a matter of debate in the current literature. We evaluated the changes in CD 1 and 3 months after femtosecond laser-assisted Keraring implantation.
Methods: This retrospective, non-comparative, multicenter, case series study included patients with keratoconus who underwent femtosecond laser-assisted implantation of double segments with 90° and 160° arc lengths or two 160° arc length Keraring segments. Demographic and baseline clinical ophthalmic data were recorded. Corneal topography and tomography data acquired using a Pentacam HR Scheimpflug tomography system (Pentacam High Resolution; Oculus, Wetzlar, Germany) with a best-fit sphere were used as a reference surface. Using the Pentacam HR, CD measurements were acquired over a corneal area of 12 mm in total and at four concentric zones (0–2, 2–6, 6–10, and 10–12 mm) of three corneal stromal depths: 120 micrometers of the anterior corneal stromal layer, 60 micrometers of the posterior corneal stromal layer, and the central layer of stroma lying between these two layers.
Results: We included 40 eyes of 40 patients, including 8 (20%) male and 32 (80%) female individuals, with a mean (standard deviation) age of 21.0 (6.4) years. We observed a significant improvement in the topographic values of steep keratometry (K), flat K, maximum K, and corneal astigmatism (all P < 0.05), but not in the mean K, thinnest corneal pachymetry, corneal thickness at the apex, back elevation, or front elevation (all P > 0.05). The mean total anterior, central, and posterior CD differed significantly among the time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05) and no difference between those of the 1-month and 3-month postoperative visits (all P > 0.05). The mean CD for the anterior layer in the central, paracentral, and mid-peripheral zones, and the central layer in all four zones, differed significantly among time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05), which remained unchanged from the 1-month to the 3-month postoperative visit (all P < 0.05), except for the central 2–6-mm zone, which decreased significantly from the 1-month to the 3-month postoperative visit (P < 0.001). The CD of the central 10–12-mm zone did not differ significantly in each pairwise comparison (all P > 0.05). In contrast, CD for the posterior layer in the paracentral zone decreased significantly from the preoperative to the 1-month and 3-month postoperative visits but increased, to a lesser extent, from the 1-month to the 3-month postoperative visit (all P < 0.05).
Conclusions: Femtosecond laser-assisted Keraring implantation significantly changes CD, with improvement in most topography parameters. Further longitudinal studies with larger sample sizes are required to verify these preliminary findings
Fenofibrate and diabetic retinopathy
Full text linkBackground: Diabetic retinopathy (DR), a sight-threatening ocular complication of diabetes mellitus, is one of the main causes of blindness in the working-age population. Dyslipidemia is a potential risk factor for the development or worsening of DR, with conflicting evidence in epidemiological studies. Fenofibrate, an antihyperlipidemic agent, has lipid-modifying and pleiotropic (non-lipid) effects that may lessen the incidence of microvascular events.
Methods: Relevant studies were identified through a PubMed/MEDLINE search spanning the last 20 years, using the broad term “diabetic retinopathy” and specific terms “fenofibrate” and “dyslipidemia”. References cited in these studies were further examined to compile this mini-review. These pivotal investigations underwent meticulous scrutiny and synthesis, focusing on methodological approaches and clinical outcomes. Furthermore, we provided the main findings of the seminal studies in a table to enhance comprehension and comparison.
Results: Growing evidence indicates that fenofibrate treatment slows DR advancement owing to its possible protective effects on the blood-retinal barrier. The protective attributes of fenofibrate against DR progression and development can be broadly classified into two categories: lipid-modifying effects and non-lipid-related (pleiotropic) effects. The lipid-modifying effect is mediated through peroxisome proliferator-activated receptor-alpha activation, while the pleiotropic effects involve the reduction in serum levels of C-reactive protein, fibrinogen, and pro-inflammatory markers, and improvement in flow-mediated dilatation. In patients with DR, the lipid-modifying effects of fenofibrate primarily involve a reduction in lipoprotein-associated phospholipase A2 levels and the upregulation of apolipoprotein A1 levels. These changes contribute to the anti-inflammatory and anti-angiogenic effects of fenofibrate. Fenofibrate elicits a diverse array of pleiotropic effects, including anti-apoptotic, antioxidant, anti-inflammatory, and anti-angiogenic properties, along with the indirect consequences of these effects. Two randomized controlled trials—the Fenofibrate Intervention and Event Lowering in Diabetes and Action to Control Cardiovascular Risk in Diabetes studies—noted that fenofibrate treatment protected against DR progression, independent of serum lipid levels.
Conclusions: Fenofibrate, an oral antihyperlipidemic agent that is effective in decreasing DR progression, may reduce the number of patients who develop vision-threatening complications and require invasive treatment. Despite its proven protection against DR progression, fenofibrate treatment has not yet gained wide clinical acceptance in DR management. Ongoing and future clinical trials may clarify the role of fenofibrate treatment in DR management
Plication or resection combined with antagonist recession in horizontal strabismus
Full text linkBackground: Strengthening of extraocular muscles is a conventional procedure in the management of strabismus. Plication may be an alternative strengthening technique, and is less invasive than resection. This study compared plication and resection, each combined with antagonist muscle recession, in terms of success rates and changes in ocular deviation in the management of horizontal strabismus.
Methods: This retrospective study recruited individuals with horizontal strabismus who underwent plication (group I) or resection (group II) coupled with antagonist muscle recession. All participants underwent a detailed baseline eye and ocular motility evaluation. Demographic and clinical data were collected, including age, sex, type of preoperative strabismus (exotropia or esotropia), baseline visual acuity, mean follow-up duration, laterality of operated eye, surgical doses of correction (resection, plication, or recession) in millimeters, preoperative strabismus magnitude in prism diopters (PD), and postoperative strabismus magnitude in PD. Successful postoperative deviation was defined as less than or equal to 10 PD. At final follow-up, the success rates and degrees of change in angle of deviation were recorded.
Results: Forty-four patients were enrolled: 19 patients in group I (plication) and 25 patients in group II (resection). The groups had comparable ages, sex ratios, types of strabismus, and preoperative and postoperative angles of deviation (all P > 0.05). Despite comparable success rates between groups (73.7% in group I versus 64.0% in group II, P > 0.05), the difference (9.7%) was marginally close to the predefined clinically meaningful difference of 10%. In the esotropia subgroup, despite comparable alignment between the plication and resection groups (P > 0.05), the difference was clinically meaningful (17.3%), and both groups had higher success rates in the esotropia subtype than in the exotropia subtype. The rate of over- or undercorrection was not statistically or clinically different in the total and in each subtype of strabismus (all P > 0.05). Success rates for unilateral and bilateral cases were similar between groups (both P > 0.05). Changes in angle of deviation were similar for individuals with esotropia and exotropia between groups (both P > 0.05).
Conclusions: In esotropic and exotropic strabismus, plication and resection procedures combined with antagonist recession were similarly effective. However, further randomized, large-scale, longitudinal studies with clinical and subjective evaluations could provide practical evidence on the suitability of the plication procedure in managing various types of strabismus
Ocular biometry parameters in mobile cataract surgery camp: a large-scale report from Nigeria
Full text linkBackground: Humanitarian missions and mobile camp surgeries have pivotal roles in the uptake of cataract surgery in areas with limited resources. Ocular biometry is an important preoperative evaluation tool for cataract surgery candidates. Herein, we report the distributions of ocular biometric values among cataract surgery candidates in camp settings in southern Nigeria.
Methods: In this cross-sectional study, we retrieved data from consecutive patients scheduled for cataract surgery. All patients underwent a full ophthalmic examination using a slit-lamp biomicroscope. Age, sex, and preoperative biometric values, including anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD), and axial length (AL), together with intraocular lens (IOL) power, were documented. Biometric values were obtained using A-mode ultrasonography.
Results: Records of 567 patients with a mean (standard deviation) age of 66.0 (13.4) years revealed a male-to-female sex ratio of 1:1.24. Most participants were in the 66–70-year age group. Mean IOL power was significantly different between males and females (P < 0.001). However, the biometric values were comparable between sexes (all P > 0.05). There were significant differences in the mean IOL power (P < 0.001) and ACD (P < 0.05) between the age groups, indicating a decrease in ACD with age. However, the other biometric parameters were comparable between the age groups (all P > 0.05). ACD had a significant weak negative correlation with LT (r = - 0.16; P < 0.001) and IOL power (r = - 0.22; P < 0.001) and a positive correlation with AL (r = + 0.24; P < 0.001). LT had a significant weak negative correlation with VCD (r = - 0.16; P < 0.001) and a positive correlation with AL (r = + 0.09; P < 0.05). VCD had significant moderate positive and negative correlations with AL (r = + 0.39; P < 0.001) and IOL power (r = - 0.34; P < 0.001), respectively. AL had a significant strong negative correlation with IOL power (r = - 0.78; P < 0.001).
Conclusions: This study presents the mean distributions of ocular biometric parameters among cataract surgery candidates in camp settings in southern Nigeria. Age and sex were important determinants of IOL power and should be considered when planning eye camp supplies. AL had a strong inverse correlation with IOL power. Further multicenter national studies are required to verify these preliminary findings
Pregnancy and diabetic retinopathy
Full text linkBackground: An increase in the worldwide prevalence of diabetes, especially among younger populations, has led to a higher prevalence of pre-existing diabetes among pregnant women. The precise mechanisms underlying the development or progression of diabetic retinopathy (DR) during pregnancy are not entirely understood. This narrative review incorporates all available data to offer fresh insights into the pathogenesis and mechanisms of the pregnancy-induced development and/or progression of DR. Moreover, the author aims to offer clinical recommendations for DR both before conception and during pregnancy to appropriately counsel these susceptible patients.
Methods: A literature search was performed using various combinations of the following keywords: diabetes, pregnancy, diabetic retinopathy, ocular, eye, retina, microangiopathy, mechanism, pathophysiology, hyperglycemia, hypoxia, neovascularization, growth factors, immune system, blood flow, and recommendations. The search was conducted using PubMed/MEDLINE, ISI Web of Science, Scopus, and Google Scholar, and only English articles published from January 1, 2020, to December 31, 2023, involving human participants, were considered. The International Diabetes Federation Diabetes Atlas website was searched for clinical recommendations.
Results: Pregnancy-induced hyperglycemia, blood flow changes, growth factors, and the immune system play important roles in the development and progression of DR. Hyperglycemia leads to significant stress on the capillary endothelium through increased glucose flux via the polyol and hexosamine pathways, activation of protein kinase C, and increased formation of advanced glycation end-products. These pathways act in several ways that may lead to increased oxidative stress, inflammation, and vascular blockage. Thus, eye examinations are crucial before, during, and up to 12 months after pregnancy. Individuals with severe non-proliferative and proliferative DR should gradually decrease their blood glucose levels to near-normal levels over a period of 6 months before conception. Statins and medications inhibiting the renin–angiotensin system should be discontinued before pregnancy or at the initial antenatal visit if they are still being used. Retinal examinations should be performed shortly after conception and during the first trimester using tropicamide eye drops and digital imaging. Subsequent examinations should be scheduled based on DR severity at the initial examination.
Conclusions: While the precise mechanism underlying the progression of DR during pregnancy remains uncertain, the available literature suggests that pregnancy-induced hyperglycemia, blood flow changes, growth factors, and the immune system play important roles in its development and progression. Pregnant women with diabetic eye manifestations benefit from the expertise of multidisciplinary teams comprising ophthalmologists, diabetologists, and gynecologists to improve both maternal and perinatal outcomes. Moreover, postpartum follow-up requires special attention