Medical Hypothesis, Discovery & Innovation (MEHDI) Ophthalmology Journal
Not a member yet
503 research outputs found
Sort by
Intracorneal ring segment implantation for eyes with keratoconus and corneas thinner than 400 microns
Full text linkBackground: Intracorneal ring segment (ICRS) implantation is a promising and effective treatment option for keratoconus. However, a corneal thickness of less than 400 microns presents a unique challenge. This study assessed the clinical course and visual outcomes in patients with Amsler–Krumeich stage 2 or greater keratoconus and clear corneas, with a minimal corneal stromal thickness of 350 microns but less than 400 microns in the proposed implantation area, up to 6 months after ICRS implantation.
Methods: This non-randomized, prospective, interventional case series was conducted at a single tertiary center, consecutively recruiting patients with keratoconus scheduled for ICRS implantation who fulfilled the eligibility criteria. Detailed ophthalmological assessments were performed at baseline and 6 months postoperatively, including measurements of uncorrected distance visual acuity (UCDVA), best corrected distance visual acuity (BCDVA), and manifest refraction with documentation of the spherical component of the refractive error (in diopters [D]), cylindrical component of refractive error (in diopter cylinder [DC]), and axis of astigmatism (in degrees). Corneal topographic and pachymetric evaluations were performed using Pentacam HR, including keratometry (K) values in D (flat K or K1, steep K or K2, and mean K or Km), corneal astigmatism in DC, central corneal thickness (CCT), and corneal asphericity coefficient (Q value).
Results: We included nine eyes of nine patients with keratoconus and a mean (standard deviation) age of 33.2 (8.2) years (range: 25–44 years). Five patients were women (56%), and four were men (44%). All eyes experienced a statistically significant improvement in the mean visual and refractive outcomes at the 6-month postoperative visit, including UCDVA, BCDVA, sphere, and cylinder (all P < 0.05). Similarly, we recorded a statistically significant improvement in the mean corneal tomographic and topographic data, including the K1, K2, Km, CCT, and Q values (all P < 0.05). No serious complications occurred for up to 6 months of follow-up. Only one patient complained of night glare, which was successfully treated with pilocarpine 1% eyedrops for 3 months.
Conclusions: ICRS implantation may offer a safe and effective option for selected patients with keratoconus and corneal thickness less than 400 microns, as evidenced by short-term improvements in visual, refractive, topographic, and tomographic parameters. No vision-threatening complications occurred. However, given the case-series study design, limited sample size, and short follow-up period, these findings should be interpreted with caution. Further controlled trials are required to validate these preliminary results.
 
Six-month longitudinal analysis of visual, tomographic, and densitometric changes after corneal collagen cross-linking in keratoconus
Full text linkBackground: Keratoconus is a progressive corneal ectasia commonly treated with corneal collagen cross-linking (CXL) to halt further progression. Although transient anterior stromal haze frequently develops after CXL, its impact on visual recovery remains unclear. This study aimed to examine the correlation between postoperative changes in corneal densitometry, visual acuity, topography, and pachymetry in eyes with keratoconus undergoing CXL.
Methods: This retrospective study included eyes with progressive keratoconus undergoing epithelium-off accelerated CXL. Pre- and postoperative assessments included measuring corrected distance visual acuity (CDVA), manifest refraction, and slit-lamp biomicroscopy examination, along with Pentacam HR imaging. Densitometry was quantified across three stromal depths and four annular zones. Follow-up evaluations were performed at day 1, week 1, and months 1, 3, and 6 post-CXL.
Results: Twenty-four eyes from 24 patients with progressive keratoconus (median age, 21.9 years; 79.2% male) were evaluated over a six-month period following CXL. At six months significant improvements were observed in CDVA, accompanied by reductions in flat keratometry, central corneal thickness, and thinnest pachymetry (all P < 0.05). Corneal densitometry increased significantly at one month and partially regressed by six months across all stromal depths and within all concentric annular zones from 0.0–2.0 mm to 6.0–10.0 mm and their corresponding total values (all P < 0.05). Baseline anterior 0.0–2.0 mm densitometry demonstrated a significant inverse correlation with CDVA (r = –0.50, P < 0.05). At one month, CDVA correlated inversely with anterior (r = –0.47, P = 0.003) and mid-stromal (r = –0.58, P = 0.006) 0.0–2.0 mm densitometry, and with anterior 2.0–6.0 mm densitometry (r = –0.45, P = 0.045). By six months, no significant correlations were found between CDVA or absolute keratometric parameters and densitometry at any depth, zone, or total value (all P > 0.05), indicating stabilization of both visual and structural recovery.
Conclusions: Accelerated epithelium-off CXL yielded significant visual and structural improvements in progressive keratoconus over six months. Corneal densitometry followed a characteristic postoperative pattern, with an early peak at one month followed by partial regression. Early stromal backscatter increases were significantly correlated with visual acuity, but these relationships diminished by six months, consistent with recovery of corneal clarity and vision. Longer-term studies are warranted to clarify the prognostic utility of densitometry for visual and tomographic outcomes after CXL
Validation of the Arabic version of the Contact Lens Dry-Eye Questionnaire-8 in Palestine
Full text linkBackground: The Tear Film and Ocular Surface Society International Workshop on Contact Lens Discomfort has stated that the Contact Lens Dry Eyes Questionnaire (CLDEQ-8) is the only validated clinical tool for assessing dry eye related to the use of soft contact lenses. Although translations of this questionnaire into various languages have been validated, the translation into Arabic has not been validated. We aimed to translate and validate the Arabic version of the CLDEQ-8 questionnaire in a clinical context among a sample of Arabic-speaking soft contact lens wearers residing in Palestine.
Methods: The CLDEQ-8 was translated into Arabic via a five-stage process: forward translation, translation revision, backward translation, refinement, and prefinal testing. The content validity of the questionnaire was assessed by a panel of 19 experts by using the Content Validity Ratio (CVR) and the Content Validity Index (CVI). After reviewing the pre-test results, the Arabic-CLDEQ-8 was finalized. For clinical validation, a web-based version of the Arabic-CLDEQ-8 was distributed to eligible soft contact lens wearers in Gaza, Palestine. Internal consistency was evaluated using Cronbach’s alpha and the Corrected Homogeneity Index.
Results: Thirty-four soft contact lens wearers, with a mean (standard deviation [SD]) age of 23.9 (5.7) years and with a mean (SD) contact lens-wear time was 10.5 (7.5) hours, including 30 (88.2%) women, completed the questionnaires. The mean (SD) score on the Arabic-CLDEQ-8 was 17.00 (6.69) (range: 2–30). Cronbach's alpha, indicating internal consistency, was 0.900, and the corrected homogeneity index exceeded 0.50 for all assessed domains, except for domain 4 (D4). The CVI and CVR were 0.73 and 0.87, respectively. Domains D1a, D1b, D2a, D3a, D3b, and D4 were found to be clear and simple, while domain D2b demonstrated an average level of content validity.
Conclusions: The trans-cultural adaptation of the CLDEQ-8 questionnaire led to the development of a reliable and valid tool for assessing the contact lens comfort among Arabic-speaking soft contact lens wearers. This Arabic-CLDEQ-8 was culturally adapted for Arabic-speaking contact lens wearers living in Palestine; thus, future studies should aim to confirm its validity in other Arabic-speaking regions
Refractive and visual outcomes of traumatic cataract surgery: a ten-year perspective
Full text linkBackground: Traumatic cataract is a major consequence of penetrating and blunt ocular injuries, often requiring surgical intervention. We evaluated the visual and refractive outcomes of traumatic cataract surgery and intraocular lens (IOL) implantation in adults who sustained open- or closed-globe injuries.
Methods: Patients who underwent cataract surgery and IOL implantation due to closed or open eye injuries were included in this descriptive-analytical, retrospective, case-series study. Eligible patients were scheduled for re-evaluation and a complete ocular re-examination, and individuals who returned and had a follow-up of at least 6 months were ultimately recruited. Because the accuracy of IOL power calculation was a primary outcome, patients who were left aphakic were excluded. Medical records were also reviewed to document baseline data, surgical details, and complications.
Results: We included 72 eyes of 72 patients with a mean (standard deviation [SD]) age of 39.5 (13.6) years and a male-to-female ratio of approximately 6:1. Forty-one (56.9%) eyes sustained open-globe injuries and 31 (43.1%) closed-globe injuries. The mean (SD) initial best-corrected distance visual acuity (BCDVA) was 1.1 (0.6) logarithm of the minimum angle of resolution (logMAR) and improved significantly to 0.3 (0.3) logMAR at the final visit (P < 0.001). A final BCDVA better than 20/40 was detected in 43 (59.7%), 23 (74.2%), and 20 (48.8%) eyes in the entire series, eyes sustaining closed-globe injuries, and those with open-globe injuries, respectively. The absolute prediction error was 1.0 diopter or less in 42 (58.3%) eyes in the entire series. A mean absolute prediction error of 1.0 D or less was more frequent in closed-globe than in open-globe injuries (n = 22 [71.0%] vs. n = 20 [48.8%], respectively). The mean absolute prediction error differed significantly between groups (P < 0.05). Eyes that sustained open-globe injury were less likely to obtain a BCDVA better than 20/40 (odds ratio, 0.33; 95% confidence interval, 0.12 – 0.91; P < 0.05).
Conclusions: Visual acuity significantly improved after traumatic cataract extraction with IOL implantation. Most cases achieved satisfactory visual and refractive outcomes. Eyes with open-globe injuries might have less favorable visual prognosis. These initial findings must be confirmed through large-scale, multi-center longitudinal studies
Update on coronavirus disease and retinal artery occlusion
Full text linkBackground: The novel coronavirus disease 2019 (COVID-19) is significant not only for its life-threatening impact, but also for its association with serious eye disorders, including retinal artery occlusion. This language-inclusive narrative review analyzed the available clinical literature on retinal artery occlusion linked to COVID-19, highlighting it as a serious vision-threatening complication of this disease during the recent pandemic.
Methods: A targeted literature search was conducted in the PubMed / MEDLINE and Google Scholar databases from January 1, 2020, to January 1, 2025, to gather the most recent evidence. Studies were identified through various combinations of the following search terms: “eye diseases in COVID-19,” “ocular findings,” “ocular manifestations in COVID-19,” “posterior segment alterations in COVID-19,” and “retinal artery occlusion in COVID-19.” Articles with relevant clinical significance were selected for review. The reference lists of these papers also manually checked for other relevant papers. We included case reports, case series, and both prospective and retrospective studies that reported cases of central retinal artery occlusion (CRAO) or branch retinal artery occlusion (BRAO) in patients of any age, sex, and race with confirmed COVID-19.
Results: We found 27 records, of which 21 reported cases of CRAO in patients with COVID-19. The mean (standard deviation) age of these patients was 54.1 (13.4) years (range: 30–77 years). Off the 21 patients, 18 (86%) were men and three (14%) were women. In three cases, bilateral involvement was noted; in one such instance, CRAO was diagnosed sequentially: in the left eye while the patient had COVID-19, and in the right eye 1.5 months later. Among the cases of unilateral CRAO, the left eye was the most frequently affected. Additionally, four cases of BRAO were reported in patients with COVID-19, with most of these patients being women. Most of these cases were diagnosed in the left eye within 1 month of a COVID-19 diagnosis. Notably, in the majority of cases involving CRAO or BRAO, vascular thromboembolic events were not reported. Additionally, two case series reported a total of 17 patients with COVID-19 who were diagnosed with CRAO.
Conclusions: Although strong evidence of a causal relationship is lacking, healthcare specialists should be aware that CRAO or BRAO may be ocular complications of COVID-19. This is particularly important with the emergence of new subvariants of SARS-CoV-2 and in asymptomatic patients, and considering the availability of rapid viral antigen tests will make it easier to check if the patient with CRAO or BRAO actually have asymptomatic COVID-19
Ocular side effects of systemic medications
Full text linkBackground: Systemic medications, which are crucial for managing a wide range of diseases from hypertension and diabetes to infections and cancers, can induce substantial ocular side effects. These effects impact visual function and quality of life, necessitating awareness and monitoring by healthcare professionals. The current review summarizes the range and mechanisms of these ocular toxicities.
Methods: This narrative review was derived from a targeted literature search using major electronic databases including PubMed/MEDLINE, Embase, Scopus, and Google Scholar. Keywords related to ocular side effects of systemic medications were utilized to identify relevant studies published from January 1, 2000, to December 30, 2024. The included articles pertained to ocular manifestations of systemic drug use, their mechanisms of toxicity, and associated management strategies.
Results: This study identified notable ocular side effects related to various systemic medications. Amiodarone was consistently linked to corneal deposits and colored halos, prompting recommendations for regular eye examinations. Isotretinoin was frequently associated with dry mucous membranes and blepharoconjunctivitis. Chloroquine and hydroxychloroquine were found to cause corneal changes and irreversible retinal damage with prolonged use. Studies of allopurinol presented conflicting evidence regarding its relationship with cataract risk. Corticosteroid use was associated with cataract formation and potential elevation of intraocular pressure. Ethambutol has been identified as a potential cause of optic neuritis. Topiramate was linked to acute angle-closure glaucoma, particularly early in treatment. Anticholinergic drugs can impact various parts of the eye. They cause ciliary muscle relaxation, leading to temporary blurred vision. This loss of accommodation, also known as “iatrogenic presbyopia,” results from paralysis of the ciliary muscle. Phosphodiesterase type 5 inhibitors, such as sildenafil, may cause pupil dilation, redness, dryness, blurred vision, and temporary cyanopsia. Additionally, patients taking vigabatrin may experience progressive constriction of the visual fields, necessitating regular visual field assessments. Epidemiological studies indicate that approximately 15% of patients taking systemic medications experience dry eye syndrome. These findings underscore the diverse range and impact of drug-induced ocular toxicities. However, vigilant monitoring and prompt management can help mitigate vision-threatening complications and preserve patients’ visual health. Addressing these ocular side effects requires strong interdisciplinary communication among ophthalmologists, optometrists, primary care physicians, and other specialists.
Conclusions: The wide range of ocular manifestations of systemic medication use emphasizes the importance of monitoring patients for these side effects. Collaborative management by eye care professionals and prescribing physicians is vital to mitigate risks. Further research must focus on the mechanisms of drug-induced ocular toxicity and developing effective preventive measures
Ocular dominance and refractive error: a cross-sectional study of 400 individuals at a tertiary eye hospital in eastern Nepal
Full text linkBackground: Ocular dominance is the consistent preference of using one eye over the other during visual processing, a phenomenon analogous to hand dominance. Ocular dominance often aligns with the eye delivering clearer vision, but does not always correspond to superior visual acuity or refractive status. Mechanisms underlying ocular dominance remain unclear, particularly in individuals whose refractive errors have remained uncorrected since childhood. In this study, we investigated ocular dominance patterns and their association with refractive error and handedness in individuals without early optical correction.
Methods: In this cross-sectional study, we recruited individuals aged 16–40 years with refractive errors, who had no history of spectacle use since childhood, from Biratnagar Eye Hospital, Nepal. Participants underwent anterior and posterior segment examinations using slit-lamp, followed by non-cycloplegic retinoscopy and subjective refraction. Ocular dominance was assessed using the Hole-in-the-Card (Dolman’s) and Miles tests. Hand dominance was determined through standardized questioning and observation during tasks. Spherical equivalents (SEQ) were calculated, and anisometropia was defined as an interocular refractive difference equal or greater than 1.00 D.
Results: Four hundred participants (mean [standard deviation, SD] age 26.1 [6.0] years; 61.3% males) were assessed for ocular and hand dominance. Refractive error SEQ ranged from +9.25 D to –13.50 D (mean [SD] –1.75 [2.46] D). Myopia was most common among students (n = 93, 23.3%) and least common among tailors (n = 14, 3.5%). The most frequent dominance pattern was right-hand combined with right-eye dominance (n = 328, 82%). A strong, statistically significant association was found between ocular and hand dominance (P < 0.01; Cramer’s V= 0.73). Moderate but statistically significant associations were observed between refractive error type and both ocular (P < 0.01; V = 0.25) and hand dominance (P < 0.01; V = 0.21). The dominant eye was not always the eye with better visual acuity. Among the 103 individuals with anisometropia (25.8%), ocular dominance was not consistently accompanied by either the higher refractive error or better visual acuity.
Conclusions: In this study, we demonstrated a strong and statistically significant association between ocular and hand dominance, suggesting existence of a significant lateralization pattern among individuals with refractive error who had no history of spectacle use since childhood. While a right-hand/right-eye dominance pattern was predominant, variations such as cross-dominance and absence of ocular dominance were also observed. A moderate but significant association was found between the type of refractive error and both ocular and hand dominance, indicating that visual and motor lateralization may influence refractive development. The dominant eye did not consistently accompany by better visual acuity or greater refractive error in individuals with anisometropia, underscoring the complexity of ocular dominance and its clinical implications. These findings may aid in understanding visual behavior and inform clinical decisions related to refractive surgeries, amblyopia management, and binocular vision assessments. Further research is needed to explore the underlying neurophysiological mechanisms
Visual outcomes for the initial 500 eyes treated with keratorefractive lenticule extraction (KLEx) for myopia and myopic astigmatism at a single-site
Full text linkBackground: Keratorefractive lenticule extraction (KLEx) has become a widely used corneal refractive surgery. Since its approval by the United States Food and Drug Administration (FDA), there are relatively few studies from large US cohorts that have evaluated visual outcomes beyond one year using KLEx for myopia and myopic astigmatism. Studies are often limited by their small sample size and short follow-up duration.
Methods: This was a retrospective study of 577 eyes from 314 patients who underwent KLEx between March 2017 and May 2024 at a single refractive surgery center. Inclusion criteria were myopia between -9.25 and -1.00 D, cylinder up to -3.00 D, and preoperative corrected distance visual acuity (CDVA) of 20/20 or better. Uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, and complications were evaluated at 3 and 12 months postoperatively. Clinical outcomes were also compared to FDA premarket trials and large international cohorts.
Results: Of 577 treated eyes, data were available at 3 months for 511 eyes (88.6% follow-up) and 12 months for 440 eyes (76.3% follow-up). Mean spherical equivalent (SEQ) improved from -5.35 ± 1.62 D (-9.63 to -1.38 D) to -0.04 ± 0.44 D (-1.88 to 1.88 D) (P < 0.001). Mean cylinder improved from -0.66 ± 0.66 D (-3.00 to 0.00 D) at baseline to -0.40 ± 0.32 D (-1.75 to 0.00 D) at 12 months (P < 0.001). Additionally, postoperative UDVA was 20/20 or better in 81% of eyes and 20/25 or better in 94% of eyes. Postoperative SEQ was within ±0.50 D in 85% of eyes and within ±1.00 D in 97% of eyes at 12 months. The SEQ remained stable across all postoperative visits, with a mean change of -0.03 ± 0.38 D from 3 to 12 months. There was a gain of one line of CDVA in 16% of eyes at 12 months, with no eyes losing two or more CDVA lines. Target-induced and surgically induced astigmatism were strongly correlated at both 3 and 12 months, with a mean undercorrection of 20% by one year (R² = 0.69).
Conclusions: KLEx demonstrates predictable and safe correction of myopia and myopic astigmatism over 12 months in a US cohort. Visual outcomes meet or exceed FDA benchmarks and are consistent with published literature, although a potential need for improved cylindrical correction remains
Crosslinking of tarsal collagen as a hypothetic therapy for dry eye disease
Full text linkBackground: Dry eye disease (DED) is one of the most prevalent and distressing ocular conditions worldwide; it primarily results from alterations in the natural tear film that covers the ocular surface and is often due to enhanced evaporation of its aqueous component. This process is frequently associated with dysfunction of the meibomian glands (MGs), which are embedded within the tarsal plate of our eyelids and secrete the meibum, an oily mixture of proteins and lipids. Meibum forms the outermost layer of the tear film, playing a critical role in controlling water evaporation and stabilizing the tear film by lowering surface tension. Meibomian gland dysfunction (MGD) may result from structural abnormalities in the MGs, such as tortuosity, which impair normal delivery of meibum. Increased laxity of the eyelid is also associated with development of MGD and DED, likely due to insufficient mechanical support for the glands, and causing morphological changes.
Hypothesis: We designed and initiated the development of a noninvasive method to strengthen and stiffen the tarsal collagen containing the embedded MGs. By reducing tissue laxity, our aim is to halt further morphological deterioration of the glands and promote uniform and smooth delivery of meibum to the ocular surface. Our previous studies showed that both mechanical tensile strength and rigidity (Young’s modulus) of tarsal collagen in animal and human eyelids were significantly enhanced by exposure to ultraviolet-A (UV-A) radiation with a wavelength of 365 nm in the presence of riboflavin as a photosensitizer.
Conclusions: We propose that performing this procedure at the initial manifestations of MGD and DED may prevent disease progression by restoring and preserving the normal morphology of the glands through reduced laxity, thereby ensuring proper secretion of the meibum into the tear film. The underlying principles and safety of the procedure were discussed in detail, and further pre-clinical evaluation steps were proposed and justified. Based on the proposed concept and the results of previous ex-vivo studies, in-vivo animal experiments and human clinical trials are currently in preparation
Ethical integrity in systematic reviews and meta-analyses: challenges, pitfalls, and best practices in ophthalmology
Full text linkBackground: Systematic reviews and meta-analyses (SRMAs) are central to evidence-based ophthalmology, influencing clinical guidelines and treatment decisions. However, the rapid increase in SRMA publications has exposed serious ethical concerns, including selective reporting, duplicate publication, plagiarism, authorship misconduct, and undeclared conflicts of interest. Despite established frameworks such as Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), International Prospective Register of Systematic Reviews (PROSPERO), and International Committee of Medical Journal Editors (ICMJE), ethical compliance remains inconsistent, undermining the credibility of synthesized evidence. We aimed to examine the ethical landscape of SRMAs with a particular focus on ophthalmology, highlighting common pitfalls, evaluating current guidelines, and providing practical recommendations to ensure that these reviews are conducted and reported with the highest ethical standards—ultimately safeguarding the integrity of the evidence base that underpins clinical eye care.
Methods: A structured literature search was conducted in PubMed, Scopus, Web of Science, and Google Scholar through May 2025 using combinations of the terms “systematic review,” “meta-analysis,” “ethics,” “research integrity,” and “ophthalmology.” Relevant guidelines, peer-reviewed studies, and editorials were synthesized to identify ethical pitfalls and propose best practice solutions.
Results: We illustrate these challenges with ophthalmology-specific examples and highlight the downstream impact of unethical SRMAs on clinical practice and public trust. We also propose actionable recommendations for researchers, editors, and institutions to enhance the ethical quality of SRMAs, including improved training in research integrity, stricter enforcement of reporting guidelines, and increased editorial oversight. By addressing these ethical dimensions, the ophthalmic community can ensure that SRMAs not only meet methodological benchmarks but also reflect the core values of scientific honesty, accountability, and patient-centeredness. Approximately one-third of ophthalmology SRMAs fail to assess bias or comply with PRISMA guidelines. Industry-sponsored reviews have shown a tendency to favor commercially linked interventions, raising objectivity concerns. Key ethical concerns include: lack of protocol registration, selective inclusion of studies, inclusion of retracted or flawed trials, duplicate or plagiarized data, and authorship and disclosure misconduct.
Conclusions: To protect the integrity of ophthalmic evidence synthesis, SRMAs must adhere to the highest ethical standards. Researchers should commit to transparent, methodologically rigorous, and ethically sound practices. Journals and institutions must enforce compliance, provide oversight, and support education in research integrity. Field-specific adaptations of reporting standards may further support ethical clarity. Ultimately, ethical SRMAs are critical to preserving trust, guiding responsible care, and fulfill their intended role as trustworthy instruments in advancing evidence-based ophthalmology