Medical Hypothesis, Discovery & Innovation (MEHDI) Ophthalmology Journal
Not a member yet
503 research outputs found
Sort by
Myopic regression after photorefractive keratectomy: a retrospective cohort study
Get PDFBackground: Myopic regression is a major complication of photorefractive keratectomy (PRK). The rates and causes vary considerably among different studies. This study aimed to investigate myopic regression at six months after myopic PRK.
Methods: In this retrospective cohort study, we included all eligible patients with myopia ranging from - 0.75 to - 9 D, aged 18 to 50 years, who underwent PRK by a single surgeon with the availability of preoperative and postoperative data at six months after the initial procedure. All participants underwent comprehensive ophthalmic examinations preoperatively and at six months post-PRK. Overcorrection was planned based on the participant’s age range to achieve the desired refractive result after PRK. All patients received the same postoperative antibiotic and steroid eye drops in a similar dosage regimen, and the contact lenses were removed after complete corneal epithelial healing. Based on the spherical equivalent of refraction six months after PRK, eyes without and with myopic regression were allocated into groups 1 and 2, respectively.
Results: We included 254 eyes of 132 patients who underwent myopic PRK with a mean (standard deviation) age of 30.12 (7.48) years; 82 (62.12%) were women and 50 (37.88%) were men. The frequency of myopic regression was significantly lower in patients with younger age, lower preoperative cylindrical refraction, and lower ablation depth (all P < 0.05). Overcorrection was more successful in eyes with low myopia than in eyes with high myopia (P < 0.05). The highest frequency of myopic regression occurred in eyes with moderate myopia (25.68%), followed by eyes with high myopia (20.0%) and low myopia (6.54%). Among different age groups, patients aged less than or equal to 30 years had a lower frequency of myopic regression. The frequency of myopic regression in the different age groups was 5.0% at 18-20 years, 7.46% at 26-30 years, 12.28% at 21-25 years, 21.31% at 31-35 years, and 26.53% at 36-50 years.
Conclusions: Overcorrection was more successful in eyes with low myopia than in eyes with high myopia. The success rate was higher in younger patients with lower astigmatism and ablation depths. Myopic regression was most frequent in eyes with moderate myopia, followed by those with high and low myopia. Further studies should replicate our findings over a longer follow-up period with a larger sample size before generalization is warranted
Intraocular lens power calculation formulas: a scientometric analysis
Get PDFBackground: The most accurate method of intraocular lens (IOL) power calculation in cataract surgery has not been determined, and further studies are needed to reach a consensus. The aim of this study was to assess publications related to IOL power calculation formulas, mapping their yearly trends, most productive authors, top publishing countries and institutions, and areas of specialization for IOL power formulas.
Methods: We conducted a comprehensive analysis of research articles published on the topic of IOL power calculation formulas. Using PubMed, we employed appropriate search terms and filtered the results for the period of January 1, 1946, to June 28, 2023. Data were analyzed using CiteSpace, VOSviewer, and Microsoft Excel programs. The visual representations of the collected data through the use of figures was provided to demonstrate the aspects of IOL power calculation research.
Results: We retrieved 5475 documents in the initial search. Analysis of these documents revealed an increase in the number of publications, from one publication in 1946 to 201 publications in 2023. The top three countries contributing to these publications were the United States, China, and Japan, collectively accounting for over 27% of the total articles. However, the two institutions with the highest contributions were located in the United Kingdom and Hungary, neither of which was among the top 10 countries in overall contributions. Overall 15326 authors contributed to publications pertaining to IOL power calculation formulas. Among these authors, the most prolific contributors included Achim Langenbucher from Saarland University (Germany), Giacomo Savini from G.B. Bietti Foundation I.R.C.C.S. (Italy), and Kenneth J Hoffer from the University of California (United States). Saarland University emerged as the most productive institution, contributing equally to two distinct departments: the Dr. Rolf M. Schwiete Center for Limbal Stem Cell Research and Congenital Aniridia, as well as the Department of Experimental Ophthalmology. The School of Physical Science at the Open University in the United Kingdom engaged in partnership with various institutions including Eye & Laser Clinic Castrop Rauxel in Germany and Johannes Kepler University Linz in Austria. Among the top 10 keywords found in the publications were “cataract”, “cataract surgery”, and “intraocular lens”.
Conclusions: This study represents the first scientometric analysis of publications related to IOL power calculation formulas. The study offers valuable insights into the geographic distribution, contributing authors, and emphasis of research on the IOL power calculation formulas. Further cooperation is essential to pinpoint the most suitable formula and to address gaps in our current understanding
A practical clinical approach to traumatic choroidal rupture
Get PDFBackground: Traumatic choroidal rupture is a posterior segment manifestation of trauma and is more common in closed-globe injuries. It is defined as a tear of the choroid and Bruch’s membrane following blunt trauma. This narrative review summarizes the current literature and provides a practical clinical approach to the diagnosis and management of traumatic choroidal rupture and its complications.
Methods: In this narrative review, we searched the PubMed/MEDLINE database using the search term choroidal rupture to provide a practical and updated approach to traumatic choroidal rupture, focusing on its definition, etiology, diagnosis, imaging, management of complications, and prognosis as mentioned in the literature over the last two decades.
Results: Traumatic choroidal rupture occurs due to increased tensile stress on the eye wall and is three-fold more common in closed-globe injuries than in open injuries. Subretinal or sub-retinal pigment epithelial hemorrhage and macular edema are early signs. Macular involvement is associated with poor visual prognosis. Damage to Bruch’s membrane increases the risk of subretinal choroidal neovascular membrane (CNVM). Traumatic epiretinal membrane is another complication. Imaging modalities such as spectral-domain optical coherence tomography, indocyanine green angiography, conventional fundus fluorescein angiography, and optical coherence tomography angiography (OCT-A) can be used in diagnosis or monitoring for complications. OCT-A offers unique opportunities for the diagnosis, treatment, and follow-up of both the initial presentation and possible complications. Frequent follow-up has been suggested in the first year after trauma. Intravitreal anti-vascular endothelial growth factor (anti-VEGF) injection is effective and less invasive in managing CNVM. The visual outcome depends on the location of the rupture, baseline visual acuity, and presence of optic atrophy or macular holes. Risk factors for developing CNVM include rupture involving the macula, longer rupture length or rupture closer to the foveal center, and older age.
Conclusions: Choroidal rupture is a posterior segment entity that usually occurs after trauma, compromises choroidal vessels and Bruch’s membrane, and can lead to CNVM. The use of novel noninvasive imaging modalities and efficient anti-VEGF therapy to manage this entity or its subsequent complications produces better visual outcomes. Early diagnosis and frequent follow-up of these patients allow treatment of possible complications, thereby improving the visual prognosis
Outcomes of the Q value-based nomogram in managing pediatric versus adult keratoconus: a prospective interventional study
Get PDFBackground: Keratoconus (KCN) is an ectatic disorder of the cornea characterized by stromal weakness and apical protrusion of the cornea, and is associated with a gradual and painless reduction in visual acuity. KCN in pediatric patients has certain important characteristics, such as a progressive and aggressive nature. We aimed to analyze the visual, refractive, and topographic outcomes of implanting a single 210° arc-length Keraring segment according to a novel, objective, Q value-based nomogram (Q-N) for the treatment of pediatric versus adult KCN.
Methods: This prospective, multicenter, non-randomized, open-label trial included 47 eyes of 47 patients who were allocated to one of two groups. The adult group included 33 eyes of patients greater than or equal to 18 years of age, whereas the pediatric group included 14 eyes of patients aged 14 – 17 years. All patients underwent femtosecond laser-assisted implantation of a single 210° arc-length Keraring segment according to the Q-N and were followed up for 6 months. All eyes underwent visual acuity measurement, cycloplegic refraction, and corneal topography at baseline and 6 months after surgery.
Results: The study groups were comparable in terms of sex proportions and KCN grades (both P > 0.05). The adult group exhibited significant postoperative improvements in mean uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), sphere, cylinder, spherical equivalent (SE), and Kmax (all P < 0.001) with a mean change of -0.56 logarithm of the minimal angle of resolution (logMAR), - 0.40 logMAR, 3.07 diopters (D), 0.70 D, 3.42 D, and - 5.26 D, respectively. The pediatric group exhibited significant postoperative improvements in mean UDVA, CDVA, sphere, SE, and Kmax (all P < 0.05) with a mean change of - 0.62 logMAR, - 0.34 logMAR, 3.18 D, 3.67 D, and - 5.37 D, respectively. There were no significant differences between the groups in terms of the mean change in visual, refractive, and topographic variables (all P > 0.05). No postoperative complications were observed in either group.
Conclusions: Use of the objective Q-N was efficient in the treatment of pediatric KCN, with postoperative improvements in the mean visual, refractive, and topographic parameters, comparable to outcomes in adult keratoconus. Q-N achieved good corneal remodeling with subsequent improvements in visual, refractive, and topographic outcomes in both adult and pediatric patients with keratoconus. To verify our preliminary findings, we recommend further multicenter randomized clinical trials using the Q-N nomogram in a larger sample of pediatric patients with KCN as an adjunct treatment before or after CXL
Safety and efficacy of eye drops from umbilical cord blood platelet lysate to treat resistant corneal ulcer
Get PDFBackground: Umbilical cord blood (UCB) is a novel treatment of resistant corneal ulcers owing to the unique anti-inflammatory molecules and growth factors it contains. Platelet lysates are a potential future alternative. The aim of the present study was to assess the role of human UCB platelet lysate in treating resistant corneal ulcers.
Methods: This was prospective, non-comparative, interventional case series involving 40 eyes of patients aged 6 – 65 years with persistent corneal ulcers from the Mansoura Ophthalmic Center and Mansoura Research Center for Cord Stem Cells. Patients were classified according to the cause of persistent corneal ulcer into four groups: group I, including 14 eyes with dry eye disease; group II, including six eyes post-keratoplasty; group III, including four eyes with corneal chemical burn; and group IV, including 16 eyes with persistent corneal ulcer from other causes. All participants underwent detailed ophthalmic examinations, and baseline and final best-corrected distance visual acuity (BCDVA) were recorded. Eye drops were prepared from UCB platelet lysate and administered to all patients along with detailed meticulous instructions for the method of use. Clinical progression of wound healing was continuously observed. The treatment response was identified as complete healing, improvement, or treatment failure.
Results: BCDVA improved significantly in all studied groups (all P < 0.05). In group I, complete healing, improvement, and treatment failure occurred in 71%, 29%, and 0% of cases. In group II, complete healing, improvement, and treatment failure occurred in 67%, 33%, and 0% of cases. In group III, complete healing, improvement, and treatment failure occurred in 50%, 50%, and 0% of cases. In group IV, complete healing, improvement, and treatment failure occurred in 63%, 12%, and 25% of cases. No adverse events associated with the treatment were observed or subjectively self-reports in the study period.
Conclusions: Eye drops from UCB platelet lysate were a novel therapeutic blood component with unique growth factors and anti-inflammatory compounds that could be an effective and safe treatment option in managing persistent corneal ulcers of different causes. A future randomized clinical trial with a large sample size and a longer follow-up is required to confirm these preliminary outcomes
Multimodal imaging in radiation retinopathy following orbital metastasis
Get PDFBackground: Radiation retinopathy is a major cause of vision loss in patients receiving radiotherapy to the head and orbit. Diabetic retinopathy is one of the differential diagnosis owing to similar clinical features, including microaneurysms, cotton-wool spots, hard exudates, and macular edema. The only significant pathological difference is that radiation retinopathy spares pericytes, unlike in diabetic retinopathy. Multimodal imaging helps diagnose and predict the prognosis of radiation retinopathy, which is presented in this case report.
Case Presentation: A 55-year-old woman diagnosed with stage-4 metastatic breast carcinoma presented with gradual diminution of vision in the left eye (OS) over 5 months. Vision in the right eye was lost because of orbital radiotherapy for orbital metastasis. The patient underwent multiple sessions of chemotherapy and radiotherapy. Examination of the left eye revealed a best-corrected distance visual acuity (BCDVA) of 20/30. Fundus examination of the OS revealed multiple cotton-wool spots and retinal hemorrhages. Fundus fluorescein angiography (FFA) showed diffuse macular leakage with capillary nonperfusion. Multicolor imaging (MCI) with Spectralis™ revealed black dots in the blue and green reflectance images, corresponding to capillary dilatation on FFA. Darker dots were more evident in the infrared images. BCDVA improved to 20/20 in OS after tapering the dose of oral steroids for 2 months, with improvements in hemorrhages and cotton-wool spots. Focal laser photocoagulation was recommended for the treatment of persistent macular edema. The patient declined further treatment, was lost to follow-up, and passed away 6 months later.
Conclusions: This case highlights the importance of multimodal imaging for the identification and classification of radiation retinopathy. MCI using SpectralisTM has been described for the first time in radiation retinopathy and can be used to complement existing imaging modalities. Future studies involving more patients and a longer follow-up duration may provide better results for the applicability of these imaging modalities in the clinical setting
Refractive errors in infants with retinopathy of prematurity treated using laser or anti-vascular endothelial growth factor monotherapy
Get PDFBackground: Infants treated for retinopathy of prematurity (ROP) could develop visually significant refractive errors. In this study, we report pre-treatment refractive errors in premature infants with treatment-requiring ROP treated using laser or anti-VEGF monotherapy and compare the components of post-treatment refractive error values between the two treatment groups at different follow-up timepoints.
Methods: In this retrospective cohort study, we analyzed 360 eyes of 181 premature infants with treatment-requiring ROP who were referred to Farabi Eye Hospital, Tehran, Iran between March 2020 and April 2021. Of the 360 eyes, 195 received laser monotherapy (laser treatment group) and 165 received an intravitreal anti-VEGF injection (anti-VEGF therapy group). All included eyes underwent pre- and post-treatment cycloplegic refraction. Cycloplegia was induced for each infant by instilling a mixed eye drop containing 1% tropicamide, 2.5% phenylephrine, and 0.5% tetracaine (in equal volumes) in each eye three times at five-minute intervals. Cycloplegic refraction was performed 30 minutes after the third instillation.
Results: The mean (standard deviation [SD]) gestational age (GA) and birth weight (BW) of the infants were 29.0 (2.0) weeks and 1241.0 (403.0) g, respectively. The male-to-female ratio in the entire study cohort was 107 (59.1%) / 74 (40.9%), whereas the ratios in the anti-VEGF therapy group and laser treatment group were 47 (56.6%) / 36 (43.4%) and 60 (61.2%) / 38 (38.8%), respectively. The pre-treatment assessment revealed that 218 (60.6%) eyes were hyperopic, 112 (31.1%) were myopic, and 30 (8.3%) were emmetropic. In the anti-VEGF therapy group, 87 (52.7%) eyes were hyperopic, 63 (38.2%) were myopic, and 15 (9.1%) were emmetropic. In the laser treatment group, 131 (67.2%) eyes were hyperopic, 49 (25.1%) were myopic, and 15 (7.7%) were emmetropic. The mean (SD) spherical refractive error and spherical equivalent of refractive error (SEQ) at the 1-week, 1-month, and > 6-month post-treatment follow-up timepoints; the mean cylindrical refractive error at the 3-month post-treatment timepoint; and the mean SEQ at the time of ROP regression were significantly different between the treatment groups (all P < 0.05). The rate of anisometropia increased significantly from 3.4% at baseline to 9.2% at the 6-month post-treatment follow-up timepoint (P < 0.05).
Conclusions: In this study, the most common pre-treatment refractive status of all included eyes with treatment-requiring ROP and eyes in each treatment group was hyperopia, followed by myopia and emmetropia. At the more than 6-month post-treatment follow-up, cycloplegic refraction revealed that the laser-treated eyes were significantly more hyperopic than the anti-VEGF-treated eyes, a finding similar to the pre-treatment refraction results. Further studies of same cohort with a longer follow-up period and a control group are needed to determine the real-world effect of each treatment modality on the refractive statuses of children treated for ROP
Contralateral eye comparison of the efficacy and safety of two artificial tear formulations for corneal subbasal nerve fiber regeneration after photorefractive keratectomy
Get PDFBackground: Currently, artificial tears (ATs) are the first-line agents for managing dry eye disease (DED). This study compared the efficacy and safety of two different AT formulations, Systane® Hydration (SH) and Systane® Ultra (SU), on symptoms of DED and regeneration of the subbasal corneal nerve fiber length (CNFL) in photorefractive keratectomy (PRK)-treated eyes.
Methods: This prospective contralateral comparative study recruited myopic eyes scheduled for PRK, and either SH or SU were administered for up to 3 months postoperatively. All participants underwent a standard comprehensive preoperative ophthalmological examination, in vivo confocal microscopy to evaluate the subbasal CNFL, and completed Ocular Surface Disease Index (OSDI) questionnaire for assessing dry eye symptoms. Image analysis software was used to calculate the subbasal CNFL (micrometer/mm2). Assessments were repeated at the 1- and 3-month follow-up visits. Pre- and postoperative subbasal CNFL and OSDI scores were compared to determine inter- and intra-group differences.
Results: Fifty eyes of 25 participants were included in this study. The mean (standard deviation) age of the participants was 22.7 (3.8) years. The OSDI scores for both groups increased significantly at 1 month (both P<0.05), followed by a decrease at 3 months to values comparable to the preoperative scores (both P>0.05). Although OSDI scores were comparable at baseline and at the 1-month postoperative visit (both P>0.05), the SU-treated eyes had a significantly better OSDI score at the 3-month visit (P<0.05), despite being clinically insignificant. Preoperative subbasal CNFL differed significantly between the groups (P=0.001), yet the mean values at both postoperative visits were comparable (both P>0.05). In both groups, subbasal CNFL was significantly reduced at 1 month, followed by a significant increase at the 3-month postoperative visit compared to baseline (all P<0.05). No treatment-related complications were observed at the end of the study period.
Conclusions: No significant difference was found between the preoperative and 3-month postoperative OSDI scores in the SH- or SU-treated eyes. Subbasal CNFL regeneration indicated a positive effect of both ATs, with a longer mean CNFL noted in the SH-treated eyes at the final visit. This suggests that SH may be a better option for improving corneal reinnervation after PRK. These observations must be verified in further trials with longer follow-up periods and larger sample sizes
Effects of repeated intravitreal bevacizumab administration on anterior segment parameters and limbal stem cells
Get PDFBackground: Macular edema (ME) is fluid accumulation in the macula caused by vascular leakage. Repeated intravitreal bevacizumab (IVB) injections are extensively used to treat ME of different origins, are well tolerated, and have few side effects. This study evaluated the effects of repeated IVB injections on the anterior segment parameters and limbal stem cells (LSCs) in eyes with ME.
Methods: This before–after study involved patients with ME of different causes who underwent repeated IVB injections at the Imam Khomeini Ophthalmology Center in Kermanshah, Iran. Before and after repeated IVB injections, anterior segment parameters were measured using anterior segment optical coherence tomography, and the LSCs were assessed using impression cytology.
Results: We enrolled 42 eyes of 42 patients with a mean (standard deviation [SD]) age of 59.6 (7.6) years, of whom 25 (59.5%) were men and 17 (40.5%) were women. The underlying diseases included diabetic ME in 30 eyes (71.4%), central (5 [11.9%]) or branch (3 [7.1%]) retinal vein occlusion, and choroidal neovascularization in 4 eyes (9.5%). The right eye was affected in 22 (52.4%) participants. The mean (SD) number of IVB injections was 4.3 (1.3). After repeated injections, the mean central corneal thickness (CCT) increased, whereas the mean anterior chamber angle (ACA) and anterior chamber depth (ACD) decreased (all P<0.001). Three patients developed LSC deficiency after repeated IVB injections for diabetic ME.
Conclusions: We observed a significant increase in the mean CCT and a decrease in the mean ACA and ACD after repeated IVB injections in our series. Three patients developed LSC deficiency after repeated IVB injections for diabetic ME management. The observed effect on LSC may cast doubt on the safety of repeated IVB injections; however, this finding must be verified in multicenter clinical trials with longer follow-up periods and larger study samples
Hypothetical proposal for the course of retinal blood vessels in the posterior pole—description and its clinical implications
Get PDFBackground: Branch retinal vein occlusion (BRVO) is the second-most common retinal vascular disorder. Arteriosclerotic changes at the site of obstruction and hemodynamic turbulence within the vessels are considered risk factors. Overcrossing of the vein by an artery has traditionally been considered to increase the risk of BRVO. Recent studies using optical coherence tomography and optical coherence tomography angiography have suggested a higher prevalence of vein-over-artery crossings in this disease. Nevertheless, uncertainty persists as to why some patients, even those with the same disease duration, have varying degrees of venous dilation and develop sufficient collaterals, while others develop substantial ischemia and its sequelae.
Hypothesis: Herein, it is hypothesized that because retinal blood vessels are transparent, tubular, and collapsible conduits coursing over a hollow spherical surface, the changes related to AV crossings over the entire course of a vessel, rather than at any single isolated crossing, could contribute to the risk, natural progression, and outcomes of BRVO. The study analyzed color fundus photographs from two image datasets. The first dataset comprised 100 randomly selected images from the author’s own collection at the Rajendra Prasad Center for Ophthalmic Sciences. The second dataset comprised 100 images from the MESSIDOR database; three images were excluded owing to poor focus. Using 394 observations from 197 retinal photographs, four distinct patterns of AV crossing along the course of blood vessels were recognized: (A and B) wicker basket, (C) straight, (D) widely spaced, and (E) indeterminate. The percentages of tight wicker, loose wicker, straight, widely spaced, and indeterminate patterns in the two image sets were 19% (38/200) and 16.5% (32/194), 22.5% (45/200) and 27.8% (54/194), 16.5% (33/200) and 15.5% (30/194), 22.5% (45/200) and 28.4% (55/194), and 19.5% (39/200) and 11.9% (23/194), respectively. Hence, the wicker basket pattern was the most common AV crossing pattern in both image sets.
Conclusions: The wicker basket pattern may provide structural stability and aid in maintaining pressure gradients within the retinal vascular bed. This observation of variable AV relationships at consecutive crossings may improve our understanding of the pathogenesis, natural history, and outcomes of BRVO. Future longitudinal studies including patients at risk of BRVO, or retrospective analyses of patients with BRVO who had ophthalmic examinations and archived fundus images before the vascular event, should verify the relevance of these observed vascular patterns