Frequency and Determinants of Visual Impairment Among Adults With Iron Deficiency Anemia at a Tertiary Care Hospital in Pakistan: Implications for Multidisciplinary and Rheumatology Care

Anemia is defined by a hemoglobin concentration below an age-, sex-, and physiological-status-specific threshold, with consideration of relevant measurement and population factors [1]. The World Health Organization continues to identify anemia as a major public health problem, particularly among young children, pregnant and postpartum women, and menstruating adolescent girls and women [2]. Global Burden of Disease estimates indicate that anemia affected approximately 1.92 billion people in 2021 [3]. Dietary iron deficiency remains one of the leading contributors to the worldwide anemia burden [4].

Pakistan continues to carry a substantial burden of anemia and iron deficiency. Studies among women of reproductive age in Quetta and Karachi have documented frequent anemia and iron deficiency [5,6]. National analyses also show persistent geographic and socioeconomic inequalities despite some improvement in anemia prevalence over time [7]. Iron deficiency may result from inadequate dietary intake, menstrual or gastrointestinal blood loss, repeated pregnancies, or impaired absorption, while interpretation of ferritin can be complicated by concurrent inflammation [8].

The eye is a metabolically active organ with high oxygen requirements, making the retina and optic nerve potentially vulnerable to sustained reductions in oxygen delivery. Reported ocular manifestations of severe anemia include conjunctival pallor, retinal hemorrhages, cotton wool spots, Roth spots, venous dilatation, optic disc edema, ischemic optic neuropathy, and, rarely, retinal vascular occlusion [9]. These abnormalities provide biological plausibility for visual dysfunction in patients with severe or prolonged iron deficiency anemia.

Structural retinal changes have also been demonstrated using optical coherence tomography (OCT). A 2024 systematic review and meta-analysis found significantly lower mean retinal nerve fiber layer (RNFL) thickness in individuals with iron deficiency anemia than in controls [10]. Individual adult studies from India and Egypt similarly reported reduced peripapillary RNFL thickness [11-13]. Structural retinal or choroidal differences have also been described in women and children with iron deficiency anemia [14-16]. Importantly, a longitudinal study reported increases in choroidal and RNFL thickness after parenteral iron replacement, suggesting that at least some OCT changes may be reversible [17].

Optical coherence tomography angiography (OCT-A) studies have extended these observations to the retinal microcirculation. Reduced macular and radial peripapillary capillary vessel density has been reported in adults with iron deficiency anemia [18,19], while altered retinochoroidal vascular plexus measurements have been demonstrated in women with iron deficiency anemia [20]. Similar vessel-density changes have been described in children [21]. Microvascular alterations have also been observed in pregnancy-associated anemia, although that population is clinically distinct from non-pregnant adults with iron deficiency anemia [22].

Functional evidence is less extensive than structural and microvascular evidence. A recent population-based analysis of US women reported associations between iron status and visual field loss, but its cross-sectional design did not establish causality [23]. In Pakistan, most anemia research has focused on prevalence, nutritional determinants, pregnancy-related outcomes, or hematological features [5-7]. The frequency of objectively measured visual impairment among Pakistani adults with laboratory-confirmed iron deficiency anemia therefore remains insufficiently characterized.

Iron deficiency is clinically relevant in rheumatology because anemia in patients with chronic inflammatory and autoimmune disorders is often multifactorial. Iron deficiency may coexist with anemia of inflammation, chronic gastrointestinal blood loss, nutritional deficiency, or treatment-related factors. Distinguishing these mechanisms is particularly important because ferritin may be elevated or appear falsely reassuring in inflammatory states. Ocular symptoms in such patients may also arise from the underlying rheumatic disease, treatment effects, or systemic anemia. Therefore, understanding anemia-associated visual abnormalities may have practical relevance to multidisciplinary rheumatology care.

The present study aimed to estimate the frequency and pattern of visual impairment among adults with laboratory-confirmed iron deficiency anemia and to examine its relationship with anemia severity, symptom duration, retinal abnormalities, and retinal nerve fiber layer thinning.

OBJECTIVES

Primary objective

To determine the frequency of visual impairment among adults with laboratory-confirmed iron deficiency anemia at a tertiary care hospital in Pakistan.

Secondary objectives

To describe the severity of visual impairment and the pattern of visual complaints and ocular abnormalities.

To determine the frequency of retinal abnormalities and retinal nerve fiber layer thinning.

To compare visual impairment across mild, moderate, and severe iron deficiency anemia.

To identify independent predictors of visual impairment after adjustment for demographic and clinical factors.

To evaluate the potential relevance of anemia-associated ocular abnormalities to rheumatology practice, particularly where iron deficiency may coexist with chronic inflammation.

Study design and setting

A prospective hospital-based observational study was conducted at Saidu Teaching Hospital, Pakistan, through the Departments of Medicine/Hematology and Ophthalmology over a 12-month period. Participants were enrolled consecutively, and ophthalmic outcomes were assessed at enrollment. The manuscript was prepared in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement [24].

Study population

The study included non-pregnant adults aged 18 to 60 years with newly diagnosed or untreated iron deficiency anemia. Recruitment occurred before initiation of definitive iron replacement whenever clinically safe and feasible.

Diagnostic criteria for iron deficiency anemia

Anemia was defined using the applicable World Health Organization hemoglobin threshold [1]. Iron deficiency was confirmed by a serum ferritin level below 15 ng/mL. When inflammation was clinically suspected, iron deficiency was accepted with ferritin below 30 ng/mL together with transferrin saturation below 20%, after clinical review, in keeping with contemporary diagnostic recommendations that emphasize cautious interpretation of ferritin in inflammatory states [8]. Microcytosis and hypochromia supported, but did not independently establish, the diagnosis.

Inclusion criteria

Eligible participants were aged 18 to 60 years, had laboratory-confirmed iron deficiency anemia, provided written informed consent, and were able to complete visual acuity testing and ophthalmological examination.

Exclusion criteria

Participants were excluded for pregnancy, known diabetes mellitus, uncontrolled hypertension, glaucoma, visually significant cataract or corneal opacity, inherited retinal disease, previous retinal vascular occlusion, optic neuritis, known neurological disease affecting vision, intraocular surgery within the preceding six months, current vitamin B12 or folate deficiency, hemoglobinopathy, active malignancy, chronic kidney disease stage 4 or 5, or inability to complete a reliable visual assessment.

Sampling technique and sample size

Non-probability consecutive sampling was used. Because no robust Pakistani estimate was available for visual impairment specifically among adults with confirmed iron deficiency anemia, an expected frequency of 20% was used for sample-size estimation. At a 95% confidence level and 5% absolute precision, the minimum required sample size was 246. After allowing approximately 10% for incomplete examinations, the planned sample size was 272 participants.

Hematological assessment

Complete blood count included hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, red cell distribution width, leukocyte count, and platelet count. Ferritin and transferrin saturation were measured. C-reactive protein was requested when inflammation was suspected. Anemia was classified as mild, moderate, or severe according to the applicable World Health Organization hemoglobin thresholds [1].

Ophthalmic assessment

Distance visual acuity was assessed in each eye separately using a standard Snellen or logMAR chart, both as presenting acuity and after best correction. Refraction was performed when presenting acuity was reduced. Near vision, pupillary reactions, ocular motility, color vision using Ishihara plates, and contrast sensitivity using the Pelli-Robson chart were assessed. Slit-lamp examination documented conjunctival pallor and anterior-segment findings. Intraocular pressure was measured, and a dilated fundus examination was performed. Color fundus photography was obtained when available.

Optical coherence tomography

Peripapillary RNFL thickness and macular ganglion cell parameters were measured using spectral-domain OCT. Scans were repeated when signal quality was below the manufacturer's recommended threshold or when segmentation was clearly incorrect. RNFL thinning was defined as an average or sectoral thickness below the fifth percentile of the device normative database in at least one eye, after exclusion of common ocular causes.

Primary and secondary outcomes

The primary outcome was visual impairment, defined for this study as best-corrected visual acuity worse than 6/12 in the better eye. Severity was graded as mild (worse than 6/12 to 6/18), moderate (worse than 6/18 to 6/60), severe (worse than 6/60 to 3/60), and blindness (worse than 3/60). Secondary outcomes included visual complaints, abnormal contrast sensitivity, color-vision abnormality, retinal abnormalities, and RNFL thinning.

Data quality

Investigators used a standardized case report form. Ophthalmic examinations were performed by an ophthalmologist or by a trained examiner under the supervision of an ophthalmologist. A 10% sample of study records was compared with source records, and classification discrepancies were resolved by consensus.

Statistical analysis

Data were analyzed using IBM SPSS Statistics for Windows, version 29.0 (IBM Corp., Armonk, NY, USA). Continuous variables were summarized as mean ± standard deviation or median with interquartile range, according to distribution. Categorical variables were summarized as frequencies and percentages. The frequency of visual impairment was reported with a 95% Wilson confidence interval. Categorical associations were evaluated using the chi-square test or Fisher exact test, as appropriate. Multivariable binary logistic regression was used to identify independent predictors of visual impairment. Adjusted odds ratios with 95% confidence intervals were reported. All tests were two-sided, and p < 0.05 was considered statistically significant.

Ethical considerations

The study protocol was reviewed by the Institutional Review Board/Ethics Committee of Saidu Teaching Hospital, which granted a waiver of full ethical review. Written informed consent was obtained from all participants before enrollment. The study was conducted in accordance with the principles of the Declaration of Helsinki [25] and applicable institutional requirements. Participant confidentiality was protected through de-identification of study records and restricted access to research data. Participants with severe anemia, retinal hemorrhage, optic disc edema, or significant visual impairment were referred promptly for appropriate medical and ophthalmological management.

Participant characteristics

A total of 286 potentially eligible patients were screened. Fourteen were excluded, including six with diabetes mellitus, three with visually significant cataract, two with vitamin B12 deficiency, two who could not complete reliable acuity testing, and one who declined participation. The final analysis included 272 participants. The mean age was 34.5 ± 9.9 years, and 232 participants (85.3%) were women. The median duration of anemia-related symptoms was 5.8 months (interquartile range, 3.3 to 9.5 months). Mean hemoglobin was 9.26 ± 1.81 g/dL, and median serum ferritin was 9.4 ng/mL (interquartile range, 6.0 to 11.7 ng/mL). Mild anemia was present in 57 participants (21.0%), moderate anemia in 159 (58.5%), and severe anemia in 56 (20.6%).

Table 1. Demographic and hematological characteristics, n = 272

                       IQR, interquartile range; SD, standard deviation.

Frequency and severity of visual impairment

Best-corrected visual impairment in the better eye was present in 48 of 272 participants, corresponding to a frequency of 17.6% (95% confidence interval, 13.6% to 22.6%). Mild visual impairment was present in 39 participants (14.3% of the total cohort), moderate impairment in eight (2.9%), and severe impairment in one (0.4%). No participant met the study definition of blindness. Visual complaints were reported by 83 participants (30.5%), most commonly blurred or reduced vision, difficulty reading or performing near work, reduced contrast, and transient visual obscurations.

Table 2. Frequency and pattern of visual impairment

                         Visual impairment categories were based on best-corrected visual acuity in the better eye.

Ophthalmological and optical coherence tomography findings

Conjunctival pallor was the most frequent examination finding and was present in 219 participants (80.5%). Abnormal contrast sensitivity was identified in 78 (28.7%), and abnormal color vision in 31 (11.4%). Retinal abnormalities were identified in 36 participants (13.2%) and included venous dilatation or tortuosity, retinal hemorrhages, cotton wool spots, Roth spots, and optic disc edema; some participants had more than one finding. RNFL thinning was identified in 66 participants (24.3%).

Table 3. Ocular and retinal findings

                       Retinal subcategories may overlap.

Factors associated with visual impairment

Visual impairment was significantly more frequent among participants with symptom duration of at least six months, hemoglobin below 8 g/dL, ferritin below 5 ng/mL, retinal abnormalities, and RNFL thinning. Age, sex, and rural residence were not significantly associated with the primary outcome in univariable analysis.

Table 4. Univariable associations with visual impairment

  P values were derived from the chi-square test or Fisher exact test, as appropriate.

Multivariable analysis

After adjustment, hemoglobin below 8 g/dL was associated with fourfold higher odds of visual impairment. Retinal abnormalities were associated with approximately 3.6-fold higher odds, and symptom duration of at least six months was associated with approximately twofold higher odds. Ferritin below 5 ng/mL and RNFL thinning did not remain independently significant after adjustment for anemia severity and retinal findings.

Table 5. Multivariable logistic regression for visual impairment

           The dependent variable was best-corrected visual impairment in the better eye.

In this hospital-based cohort, visual impairment was present in approximately one in six adults with iron deficiency anemia. The frequency was higher among participants with severe anemia, prolonged symptoms, retinal abnormalities, and RNFL thinning in univariable analyses. After adjustment, hemoglobin below 8 g/dL, symptom duration of at least six months, and retinal abnormalities remained independently associated with visual impairment. Because the study was conducted at a single tertiary-care center, the observed frequency should be interpreted as a clinical cohort estimate rather than a population prevalence for Pakistan.

The structural findings are consistent with the broader OCT literature. The 2024 meta-analysis by Ghasemi and colleagues demonstrated lower pooled RNFL  thickness in patients with iron deficiency anemia compared with controls [10]. Joshi and Ingle reported reduced average peripapillary RNFL thickness in adults with iron deficiency anemia [11], while Das Gupta and colleagues found similar reductions in nutritional-deficiency anemia, including the iron-deficiency subgroup [12]. El-Gamal and colleagues also reported peripapillary RNFL differences in iron deficiency anemia [13]. Studies in children and women have described related structural retinal and choroidal abnormalities [14-16].

The microvascular literature provides a complementary mechanism. Koca and colleagues reported reduced macular and radial peripapillary vessel density on OCT-A in adults with iron deficiency anemia [18]. Düzgün and colleagues identified altered retinochoroidal vascular plexus measurements in affected women [20], and Kocer and colleagues demonstrated reduced radial peripapillary capillary density that correlated with hematological indices [19]. Pediatric OCT-A data have likewise shown lower peripapillary and macular vessel density [21]. Findings from pregnancy-associated anemia also demonstrate that systemic anemia can be accompanied by quantifiable retinal microvascular changes, although pregnancy represents a distinct physiological state and should not be directly generalized to the present cohort [22].

The association between hemoglobin below 8 g/dL and visual impairment is clinically plausible. Severe anemia reduces arterial oxygen-carrying capacity and may compromise retinal oxygen delivery, particularly when chronic or accompanied by microvascular abnormalities. Retinal hemorrhages, cotton wool spots, disc edema, and rare retinal arterial occlusion have been described in severe iron deficiency anemia [9]. The finding that retinal abnormalities remained independently associated with visual impairment in the present analysis further supports the clinical relevance of fundus assessment when visual symptoms occur.

The relationship between RNFL thinning and visual impairment was more nuanced. RNFL thinning was associated with visual impairment in univariable analysis but did not remain significant after adjustment. This may indicate confounding by anemia severity or coexisting retinal abnormalities, or it may reflect limited power to distinguish overlapping structural pathways. Importantly, Coban and colleagues documented increases in RNFL and choroidal thickness after parenteral iron replacement [17], raising the possibility that some structural changes may be at least partially reversible. Longitudinal studies linking correction of anemia to repeat visual function and OCT measurements are therefore needed.

Functional outcomes have been studied less extensively than structural imaging. A 2025 NHANES analysis reported an inverse association between transferrin saturation and visual field loss among US women aged 40 to 49 years, and iron deficiency definitions were associated with higher odds of visual field loss [23]. Those data are not directly comparable with the present study because of differences in population, exposure definition, and visual outcome, but they reinforce the need to examine functional as well as structural ocular consequences of impaired iron status.

Pakistani anemia research has predominantly focused on women of reproductive age, nutritional determinants, and geographic or socioeconomic variation [5-7]. Women also constituted most of the present cohort, which is consistent with the recognized clinical burden of iron deficiency among women of reproductive age. However, the relatively small male subgroup limits sex-specific inference, and the single-center design restricts generalizability across regions and healthcare settings.

These findings may have particular relevance to rheumatology practice, where anemia is frequently multifactorial and iron deficiency may coexist with anemia of inflammation. In patients with chronic inflammatory or autoimmune disorders, ferritin can be difficult to interpret because it behaves as an acute-phase reactant, making assessment of transferrin saturation and inflammatory markers clinically important. In addition, visual complaints in patients attending rheumatology services may have several potential explanations, including ocular manifestations of the underlying rheumatic disorder, treatment-related effects, and systemic hematological abnormalities. Recognition of severe or persistent iron deficiency may therefore help identify patients who warrant formal ophthalmological assessment. The present cohort was not selected according to rheumatic diagnosis, so these observations should be interpreted as clinically relevant, hypothesis-generating evidence rather than disease-specific rheumatology findings [8].

More broadly, experimental and clinical studies in other inflammatory and metabolic settings have shown that antioxidant or metabolic interventions can modify inflammatory and oxidative-stress pathways [26,27]. These studies do not establish a mechanism for anemia-related visual impairment and were not conducted in rheumatology cohorts. They are cited only as broader biological context for the interaction between systemic metabolic or inflammatory states and tissue oxidative stress, an area that warrants direct investigation in anemia and ocular disease.

This study had several strengths. Iron deficiency was laboratory confirmed, major alternative causes of visual impairment were excluded, best-corrected rather than presenting visual acuity was used for the primary outcome, and participants underwent fundus examination and OCT. Important limitations include the absence of a non-anemic control group, potential referral bias from a single tertiary center, possible inflammation-related misclassification of ferritin, the predominantly female sample, and the cross-sectional timing of the ophthalmic assessment. The observational design cannot establish that iron deficiency caused the visual abnormalities observed.

Future multicenter studies should include non-anemic comparison groups and standardized assessment of inflammatory markers, visual fields, contrast sensitivity, and OCT/OCT-A. Longitudinal reassessment after correction of iron deficiency would be particularly valuable. Demonstration that visual or structural abnormalities improve in parallel with hematological recovery would strengthen causal inference and help identify which ocular changes are clinically reversible.

Visual impairment was identified in 17.6% of adults with laboratory-confirmed iron deficiency anemia in this hospital-based cohort. Hemoglobin below 8 g/dL, symptom duration of at least six months, and retinal abnormalities were independently associated with visual impairment. These findings support heightened attention to visual symptoms and consideration of formal ophthalmic assessment in patients with severe or prolonged iron deficiency anemia. Larger multicenter and longitudinal studies are needed to determine generalizability and to assess whether correction of iron deficiency improves visual outcomes. These observations may be particularly relevant to multidisciplinary and rheumatology care, where iron deficiency can coexist with chronic inflammation and where visual complaints may have overlapping systemic, inflammatory, and ocular causes. Future studies specifically enrolling patients with rheumatic diseases are warranted to determine whether anemia severity and iron status are associated with ocular abnormalities in these populations.

World Health Organization. Guideline on haemoglobin cutoffs to define anaemia in individuals and populations. Geneva: World Health Organization; 2024.

2. World Health Organization. Anaemia. Geneva: World Health Organization; 2025.

3. GBD 2021 Anaemia Collaborators. Prevalence, years lived with disability, and trends in anaemia burden by severity and cause, 1990-2021: findings from the Global Burden of Disease Study 2021. Lancet Haematol. 2023;10(9):e713-e734. doi:10.1016/S2352-3026(23)00160-6.

4. Safiri S, Kolahi AA, Noori M, Nejadghaderi SA, Karamzad N, Bragazzi NL, et al. Burden of anemia and its underlying causes in 204 countries and territories, 1990-2019: results from the Global Burden of Disease Study 2019. J Hematol Oncol. 2021;14(1):185. doi:10.1186/s13045-021-01202-2.

5. Qadir MA, Rashid N, Mengal MA, Hasni MS, Kakar SUD, Khan GM, et al. Iron-deficiency anemia in women of reproductive age in urban areas of Quetta District, Pakistan. Biomed Res Int. 2022;2022:6677249. doi:10.1155/2022/6677249.

6. Ashraf F, Uddin MMN, Mustafa MS, Mughal ZUN, Aleem SA. Prevalence and factors influencing anemia in women of reproductive age visiting a tertiary care hospital (Jinnah Postgraduate Medical Center) in Karachi: a cross-sectional study. Womens Health (Lond). 2024;20:17455057241227364. doi:10.1177/17455057241227364.

7. Owais A, Habib A, Ahsan H, Merritt CE, Lee C, Islam M, et al. Drivers of anemia reduction among women of reproductive age in Pakistan: a mixed-methods country case study. Am J Clin Nutr. 2025;121(Suppl 1):S46-S56. doi:10.1016/j.ajcnut.2024.04.037.

8. Iolascon A, Andolfo I, Russo R, Sanchez M, Busti F, Swinkels D, et al. Recommendations for diagnosis, treatment, and prevention of iron deficiency and iron deficiency anemia. HemaSphere. 2024;8(7):e108. doi:10.1002/hem3.108.

9. Deb AK, Subramaniam S, Sarkar S, Suneel S, Elamurgan V, Kaliaperumal S. Branch retinal artery occlusion as an initial ocular manifestation of severe iron deficiency anemia: a rare case report. Taiwan J Ophthalmol. 2022;12(2):227-230. doi:10.4103/tjo.tjo_70_20.

10. Ghasemi M, Ghasemi A, Khorasani S, Zare S, Sazgar AK, Nikkhah H. Characteristics of optical coherence tomography in patients with iron deficiency anemia: a systematic review and meta-analysis. BMC Ophthalmol. 2024;24(1):483. doi:10.1186/s12886-024-03751-9.

11. Joshi RS, Ingle RN. Peripapillary nerve fiber layer in patients with iron deficiency anemia: a cross-sectional study in a tertiary eye care center in Central India. Oman J Ophthalmol. 2023;16(2):263-267. doi:10.4103/ojo.ojo_252_22.

12. Das Gupta S, Dhawan A, Kakkar A, Shakeel T, Verma A. Effect of nutritional-deficiency anemia on peripapillary retinal nerve fiber layer: a North Indian study. Taiwan J Ophthalmol. 2023;13(2):210-218. doi:10.4103/tjo.TJO-D-22-00142.

13. El-Gamal SSA, Zaky AG, El-Sawy MF. Retinal nerve fiber layer thickness evaluation in iron deficiency anemia patients using optical coherence tomography. Delta J Ophthalmol. 2022;23(1):29-36. doi:10.4103/djo.djo_50_21.

14. Abd Al Basset E. Evaluation of peripapillary retinal nerve fiber layer by optical coherence tomography in children with iron deficiency anemia. Benha Med J. 2022;39(1):108-116.

15. Ugurlu A, Tasli NG, Icel E. Assessment of retinal and choroidal alterations in women with iron-deficiency anemia: an optical coherence tomography study. Cerrahpasa Med J. 2021;45(3):167-172. doi:10.5152/cjm.2021.21016.

16. Samant S, Mishra S, Mohanty S, Pareek D, Dhar SK, Panigrahi PK. Analysis of retinal nerve fibre layer thickness and optic disc parameters in patients of iron deficiency anaemia. J Assoc Med Sci. 2022;55(3):1-6.

17. Coban F, Kaplan FB, Akkaya S, Okuroglu N, Acikalin B. Evaluation of optical coherence tomography parameters before and after parenteral iron treatment of patients with iron deficiency anemia. Photodiagnosis Photodyn Ther. 2023;43:103713. doi:10.1016/j.pdpdt.2023.103713.

18. Koca S, Bozkurt E, Erogul O, Yavasoglu F, Dogan M, Akdogan M. Evaluation of macular and optic disc radial peripapillary vessel density with optical coherence tomography angiography in iron deficiency anemia. Photodiagnosis Photodyn Ther. 2022;38:102744. doi:10.1016/j.pdpdt.2022.102744.

19. Kocer AM, Kiziltoprak H, Fen T, Goker YS, Acar A. Evaluation of radial peripapillary capillary density in patients with newly diagnosed iron deficiency anemia. Int Ophthalmol. 2021;41(2):399-407. doi:10.1007/s10792-020-01589-w.

20. Duzgun E, Demir N, Alkan AA, Uslu Dogan C, Cakir A. Retinochoroidal vascular plexuses in patients with iron deficiency anaemia. Clin Exp Optom. 2022;105(3):326-332. doi:10.1080/08164622.2021.1916387.

21. Korkmaz MF, Can ME, Kazanci EG. Effects of iron deficiency anemia on peripapillary and macular vessel density determined using optical coherence tomography angiography on children. Graefes Arch Clin Exp Ophthalmol. 2020;258(9):2059-2068. doi:10.1007/s00417-020-04633-8.

22. Wu Y, Wang D, Wu X, Shen L, Zhao L, Wang W, et al. Optical coherence tomography angiography for the characterisation of retinal microvasculature alterations in pregnant patients with anaemia: a nested case-control study. Br J Ophthalmol. 2024;108(1):117-123.

23. He L, Zheng J, Shi Q, Liu L, Zhong J, Sha X. Association of iron status with visual field loss in US females: data from National Health and Nutrition Examination Survey (NHANES) 2005-2008. BMC Public Health. 2025;25(1):553. doi:10.1186/s12889-025-21631-9.

24. von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007;370(9596):1453-1457. doi:10.1016/S0140-6736(07)61602-X.

25. World Medical Association. World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA. 2013;310(20):2191-2194. doi:10.1001/jama.2013.281053.

26. Sultan S, Zoofeen U, Shah I, Bukhari SMS, Sharif N, Bukhari SKS, Khan M, Habib SH, Shah FA, Alamoudi MK, Shah M. Enhanced inflammatory and oxidative response mitigation by acetyl-L-carnitine in a rat model of pelvic inflammatory disease. Naunyn Schmiedebergs Arch Pharmacol. 2025;398(7):9215-9224. doi:10.1007/s00210-025-03858-w.

27. Shah FA, Bukhari SMS, Emal E, Shah M. Effects of integrative administration of acetyl-L-carnitine, arginine, and Co-Q10 in mitigating oxidative stress in over-weight/obese PCOS women. J Appl Pharm Sci. 2025;15(4):274-282. doi:10.7324/JAPS.2025.70521.