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 Table of Contents  
Year : 2021  |  Volume : 30  |  Issue : 5  |  Page : 538-542

Pattern of diabetic retinopathy in a tertiary healthcare facility in Southern Nigeria

1 Department of Ophthalmology, University of Calabar; Department of Ophthalmology, University of Calabar Teaching Hospital, Calabar, Nigeria
2 Department of Ophthalmology, University of Calabar, Calabar, Nigeria
3 Department of Internal Medicine, University of Calabar; Department of Internal Medicine, University of Calabar Teaching Hospital, Calabar, Nigeria
4 Department of Family Medicine, Federal Medical Centre, Asaba, Nigeria

Date of Submission12-Jul-2020
Date of Decision16-Feb-2021
Date of Acceptance19-Aug-2021
Date of Web Publication11-Oct-2021

Correspondence Address:
Dr. Chineze Thelma Agweye
Department of Ophthalmology, University of Calabar, Calabar
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/NJM.NJM_216_20

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Objective: The objective is to determine the pattern and prevalence of diabetic retinopathy (DR) among patients living with diabetes mellitus. Methodology: Descriptive cross-sectional study in a tertiary hospital. Questionnaires were used to obtain data from eligible participants. Visual acuity measurement, fundal examination, and photography were performed together with fasting blood glucose and glycated hemoglobin A1c. The Statistical Package for Social Sciences (SPSS) for Windows version 20 was used for data analysis. Results: Overall 200 patients were enrolled of which 75.5% were female. The participant's mean age was 53.8 ± 11.7 years. DR was present in 53/200 (26.5%) of participants, of which 52 (98.1%) had nonproliferative DR (NPDR), and 1 (1.9%) had proliferative DR (PDR). NPDR was mild in 44/53 (83.0%) and moderate in 8/53 (15.1%) patients. Evidence of sight-threatening DR was found in 37/200 (18.5%) of participants (36 had diabetic macular edema and 1 had PDR + DMO). Conclusions: DR was present in 26.5% of the study participants, and 18.5% had sight-threatening DR mainly due to DMO. This finding underscores the need for routine screening of all people living with diabetes to detect early DMO and provide treatment to prevent visual loss.

Keywords: Diabetes mellitus, diabetic macular edema, nonproliferative diabetic retinopathy, prevalence

How to cite this article:
Agweye CT, Ibanga AA, Udoh MME, Enang OE, Nwajei AI, Nkanga DG. Pattern of diabetic retinopathy in a tertiary healthcare facility in Southern Nigeria. Niger J Med 2021;30:538-42

How to cite this URL:
Agweye CT, Ibanga AA, Udoh MME, Enang OE, Nwajei AI, Nkanga DG. Pattern of diabetic retinopathy in a tertiary healthcare facility in Southern Nigeria. Niger J Med [serial online] 2021 [cited 2021 Dec 8];30:538-42. Available from: http://www.njmonline.org/text.asp?2021/30/5/538/327957

  Introduction Top

Diabetes mellitus (DM) is of public health importance globally[1] with an estimated 463 million adults currently living with the disease.[2] In Africa, 19.4 million adults within the age group of 20–79 years are estimated to have DM. DM can result in life and sight-threatening multiorgan complications, including diabetic retinopathy (DR).[3],[4]

Globally, DR accounts for 3.28 million people experiencing moderate-to-severe visual impairment and 1.07 million people been blind.[5] It is the major cause of blindness and visual impairment among adults living with DM in the working-age group.[6] DR can be broadly divided into nonproliferative DR (NPDR) and proliferative DR (PDR).[3] Either of the subtypes of DR can be further categorized as mild, moderate, or severe. Patients with DR can develop diabetic macula edema (DMO), which involves retinal thickening in the macula area at any stage of the different categories of the disease.[7] PDR and DMO are vision-threatening and are identified as causes of visual impairment and/or blindness.[4],[8] Evidence from clinical trials has shown that the treatment of PDR and DMO is critical in preserving vision;[9] hence, blindness from PDR and DMO is potentially avoidable.[4],[10]

The magnitude of DR is influenced by the prevalence of DM, availability of healthcare services for a person living with DM, and their health-seeking behavior. The National Blindness and Visual Impairment Survey (NBVIS, 2007) reported that 20.5% of diabetics had DR,[10] of which 62.2% had vision-threatening DR (VTDR).[10]

There is currently a paucity of information. The aim of the study was to generate evidence on the prevalence and pattern of DR among patients with DM being managed at the University of Calabar Teaching Hospital (UCTH), Cross River state. Information will be used in planning, implementation, and evaluation of the DR screening and treatment services in the facility and may also be useful for planning services in other parts of Nigeria.

  Methodology Top

Study site

The study was conducted in the DR screening clinic at the UCTH/LIONS Diabetes Centre, Calabar. This clinic runs concurrently with the endocrinology clinic, where patients with metabolic and endocrine disorders, including diabetes, are seen. On average, between 40 and 60 patients living with diabetes are seen per week; an average of 240 patients in a month is attended to in this clinic.

All the patients seen at the DR screening clinic had visual acuity assessment and dilated fundoscopy done by the ophthalmologist (CA). Fundus photography was performed on all patients by a trained screener/grader, and the findings of the photography were reviewed and confirmed by the ophthalmologist (CA). If DR was found, patients were referred to the medical retina service at the eye clinic, and patients with no DR were recalled annually for follow-up.

Study design

A cross-sectional, descriptive study was carried out among old and newly diagnosed patients living with diabetes attending the UCTH/LIONS Diabetes Clinic. The study was for four months, conducted from March to June 2016.

Inclusion criteria

Patients aged 18 years and above that met the case definition of DM of fasting blood glucose ≥6.0 mmol and glycated hemoglobin ≥7%.[11]

Exclusion criteria

Patients with dense cataracts obscuring the visualization of the retina on dilation, those that were too ill for an eye examination, and nonconsenting clinic attendees.

Study size

The Leslie Kisch formula for single proportion was used to calculate the sample size.[12] Based on a previous study, the prevalence of 12.75% of diabetics having DR,[13] z of 1.96, and sampling error of 0.05 a minimum sample size of 171 was obtained. To make an allowance for 10% attrition of study participants, the minimum sample size was increased to 189.

Sampling technique

Using the systematic sampling technique, 200 study participants were selected after the sample size was determined. They were chosen at regular intervals from the sampling frame which was the clinic list for each day. The sampling interval calculation was done using the formula K = N/n. which was approximately 5. Using the balloting method, 5 pieces of paper of equal sizes with “yes” written on one and “no” written on the remaining 4 were folded up, put in a non-transparent bag, and shuffled. Participants with serial numbers 1–5 on the clinic list for that day were made to pick blindly from the bag. The study participant among the 5 who picked “yes,” met the study criteria for recruitment, and consenting to participate was regarded as the starting point. Subsequently, every eligible fifth participant was selected until the desired sample was obtained. If a selected participant had been enrolled in the study the previous week, he/she was skipped and the next eligible person chosen. Approximately 10–15 eligible participants were selected weekly to make up the sample size of 200.

Study procedure

Patients' biodata and anthropometric measurements at the entry point into the study were recorded together with fasting blood glucose measured using Finetest glucometer and test strip (infopia Co Ltd, Korea), and glycated hemoglobin using Clover* A1c self-analyzer and Clover* A1c self-test Cartridge INFHS01AS (infopia Co Ltd, Korea).

The distance visual acuity for each eye was done using an illuminated Snellen literate or illiterate E-chart. This included unaided, pinhole, and aided (with glasses, if available). Near vision was assessed binocularly using Rayner's chart held at 40 cm from the eyes. The anterior segment of the participants' eyes was examined with a slit lamp biomicroscope for any abnormalities; thereafter, pupils were dilated using topical Tropicamide (0.8%) + Phenylephrine (5%) for dilated ophthalmoscopy with a + 78D Volk lens.

A certified DR screener performed fundal photography using a NAG FF 450 Plus retinal camera by Carl Zeiss. Optical coherence tomography (OCT) using a Stratus OCT model 3000 was performed in the presence of hard exudate and retinal thickening at the macula to determine the severity of diabetic macular edema (DMO) and guide management. DR grading was performed on all patients using the International Classification of DR and Diabetic Macular Edema scale.[14] The presence of PDR and/or DMO was used to define sight-threatening retinopathy.

Participants found to have DR were counseled and referred to the medical retina unit for appropriate treatment and follow-up.

Data management

Descriptive statistics included frequencies, mean and standard deviations using Statistical Package for Social Sciences (SPSS) for Windows (version 20, SPSS Inc. Chicago IL, USA).

Ethical considerations

The UCTH health research ethics committee approved the study. Before enrolment into the study, participants gave informed consent. Their confidentiality was protected.

  Results Top

Two hundred participants with DM were enlisted in the study. The range for age was 21 years to 79 years with a mean of 53.8 ± 11.7 years. There were 151 (75.5%) females with a male to female ratio of 1:3 as seen in [Table 1].
Table 1: Sociodemographic of participants

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[Table 2] shows that of the 200 participants, 54% had DM for 5 or more years.
Table 2: Duration of diabetes mellitus among participants

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DR was present in 53/200 (26.5%) of the study sample [Figure 1], with 44 (22.0%) having mild and 8 (4.0%) moderate NPDR and 1 person (0.5%) had PDR. 37/200 (18.5%) of the participants had DMO or PDR, which is sight-threatening [Table 3].
Figure 1: Prevalence of diabetic retinopathy amongst DM patients attending the Diabetic Clinic in University of Calabar Teaching Hospital /Lions Diabetes Center, Calabar

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Table 3: Diabetic retinopathy in 200 patients with diabetes mellitus

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  Discussion Top

DR prevalence in this study population was found to be 26.5%, of which 18.5% had associated DMO. Mild NPDR was the most common type of DR among the study population. Of the 200 patients, 37 (18.5%) had sight-threatening DR requiring treatment, of which only 1 in this sample had PDR.

Variance in the prevalence of DR in hospital-based studies was observed. A prevalence of 26.5% for DR was noted in this study. It is lower than 28.6% and 33% reported by Nkanga et al. and Nwosu in Nigeria, respectively[15],[16] and those reported in India 31.5%, Saudi Arabia 36.4%, Oman 42.4%, Egypt 42%, and Jordan 64%.[17],[18],[19],[20],[21] The prevalence in this study was comparable to that observed in China.[22] The prevalence of DR observed in the study was in the range of 7.0%–64.5% noted in diabetes clinic-based surveys in sub-Saharan Africa.[23] The DR prevalence in our study was observed to be higher compared to other studies; 12.3% in Spain, 12.8% in Enugu, and 21.9% in Australia.[13],[24],[25] The regional variations in prevalence and control of DM, demographic pattern in population, differences in methods of detection of DR, and study method could account for the variation in prevalence between the index study and other studies.[15],[16],[17],[18],[19],[20],[21]

Mild NPDR was the most prevalent type of DR. This is comparable to the study by Nwosu in South-Eastern Nigeria, where mild DR was the prevalent pattern.[16] It is also consistent with findings from hospital-based studies in Nepal and Saudi Arabia.[18],[26] However, it differs from reports of studies from Kano and Ondo states of Nigeria and Kenya which identified moderate and severe NPDR as the most prevalent pattern of DR.[27],[28],[29] The differences observed may have been due to the method of detection of DR. The reason for the high proportion of mild NPDR in this study could be because nearly half of the patients had DM for 5 years or less. A long-standing DM of 10 years and above is associated with DR and its progression.[30],[31]

VTDR due to PDR and/or DMO occurred in 18.5% of the participants. Our study is higher than that observed in Saudi Arabia and other global studies[32],[33] but lower than those observed in China and Northern and Western parts of Nigeria.[10],[34] The observed difference could be due to the duration of DM of the participants or the method of detection of DR. The investigators in the study conducted in the Western part of Nigeria used direct ophthalmoscope[27] to detect DR as against indirect ophthalmoscope and fundus photography used in this study.

Participants with VTDR were referred to the medical retina unit of the ophthalmology department UCTH, where they were evaluated and treated with either laser, intravitreal anti-VEGF injection, or had a vitreoretinal consult. Although mild NPDR as an entity is not vision-threatening, it can progress to the more severe forms of NPDR, PDR, or coexist with DMO with consequent blindness or visual impairment.

Maintaining and improving eye health which includes early diagnosis and adequate treatment of DR will improve quality of life, increase productivity and help in the attainment of sustainable development goals, which include reduction in poverty, gender equality, and decent work.[35],[36],[37] Therefore, it is imperative for all stakeholders entailed in the management of patients living with diabetes to ensure the formulation of a local and national clinical guideline for the comprehensive management of DM with emphasis on yearly eye examination for prompt detection and treatment of persons with DR. This approach can avert severe visual impairment and avoidable blindness.

  Conclusions Top

About one-fourth of the patients with DM in this study had DR, and nearly 1 in 5 had sight-threatening DR requiring treatment. Routine screening of patients living with DM for DR and DMO will facilitate early detection and treatment of the condition. This measure will prevent disease progression and reduce the risk of blindness from DM.


The authors are indebted to all staff and patients of the UCTH/Lions Diabetes Centre for their support and cooperation during this study. We are also indebted to our VISION 2020 LINKS Partners; The Royal Wolverhampton NHS Trust, the DR NETWORK, The Commonwealth Eye Health Consortium (CHEC), and the VISION 2020 LINKS Coordinating office at the ICEH, LSHTM, London, which sponsored both fellowship and specific training in DR Screening and grading for team members.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1]

  [Table 1], [Table 2], [Table 3]


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