OCT-Based Screening for Early Retinal Changes in Asymptomatic Diabetic Patients

Overview

The goal of this observational study is to detect early retinal changes in people with diabetes who do not have visual symptoms. The study will use Optical Coherence Tomography (OCT) and fundus examination to screen for early retinal involvement in diabetic patients. The main questions this study aims to answer are: Can OCT detect early retinal changes before symptoms appear in people with diabetes? Is fundus examination useful for identifying early diabetic retinal changes? Participants will undergo a comprehensive eye examination, including OCT macular scans and fundus examination, at Assiut Ophthalmology Hospital. No treatment or invasive procedures will be performed as part of this study. The collected data will help improve early detection and prevention of diabetic retinal complications.

Detailed description

Diabetic retinopathy is a leading cause of vision impairment worldwide. Even in the absence of visual symptoms, patients with diabetes may already have early structural retinal changes that can be detected only with advanced imaging. Identifying these changes at an early stage is essential to prevent progression to vision-threatening complications.

This observational cross-sectional study aims to evaluate the role of Optical Coherence Tomography (OCT) and fundus examination in detecting early retinal changes among diabetic patients with no visual complaints. The study will be conducted at the Ophthalmology Department, Assiut University Hospitals, Egypt.

Eligible participants will include individuals with a confirmed diagnosis of type 1 or type 2 diabetes mellitus for at least six months, best-corrected visual acuity of 6/6, clear ocular media, and no clinical evidence of retinal disease. A control group of healthy subjects with normal ocular findings will also be included for comparison.

All participants will undergo a complete ophthalmic assessment that includes:

Medical and ocular history, including diabetes duration and systemic status.

Visual acuity measurement (uncorrected and best-corrected) using the Snellen chart.

Anterior segment evaluation by slit-lamp biomicroscopy.

Fundus examination using slit-lamp biomicroscopy.

Spectral-domain OCT macular scanning (NIDEK RS-330, Japan) for assessment of macular thickness and retinal layer structure.

Data will be analyzed using SPSS software (Version 16). Quantitative variables will be expressed as mean ± standard deviation and compared using appropriate statistical tests. Correlations between OCT parameters, disease duration, and HbA1c levels will be evaluated.

The study is non-interventional and poses no significant risk to participants, as it involves only routine, non-invasive ophthalmic imaging. The findings are expected to improve early detection strategies for diabetic retinal changes and support the use of OCT and fundus examination as effective screening tools in routine diabetic eye care.

The estimated sample size will include approximately 112 participants (56 diabetic patients and 56 healthy controls).

Interventions

• Diagnostic test Spectral Domain OCT Imaging
  Non-invasive spectral domain optical coherence tomography(SD-0CT) imaging using a NIDEK RS-330 device to measure central macular , parafoveal, and perifoveal thickness and to assess the structural integrity and layers of the retina. This is a diagnostic procedure performed for observation only.

Primary outcome measures

• Comparison of retinal thickness parameters between diabetic patients and healthy controls [Time frame: Baseline ( single assessment at the time of enrollment )]

Secondary outcome measures (1)

• Correlation between OCT changes and duration of diabetes/HbA1c level [Time frame: Baseline ( single assessment at the time of enrollment )]

Eligibility criteria

Inclusion criteria

• Confirmed diagnosis of type 1 or type 2 diabetes mellitus for at least 6 months
• Best-corrected visual acuity (BCVA) of 6/6 using Snellen chart
• No visual symptoms (no blurred vision or metamorphopsia)
• Clear ocular media allowing high-quality OCT imaging
• No significant abnormalities on fundus examination
• Intraocular pressure (IOP) below 21 mmHg
• Willing and able to provide written informed consent

Exclusion criteria

• History of previous macular disease or treatment (laser photocoagulation or intravitreal injection)
• Media opacity that prevents adequate OCT imaging (e.g., dense cataract, corneal opacity)
• Presence of other retinal diseases (e.g., age-related macular degeneration, retinal vein occlusion)
• Systemic or neurological diseases that affect the retina or visual pathway
• Uncooperative participants or those who decline to give consent

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Observational model

Case-control

Study locations

Center list to be confirmed — check the primary protocol.

Publications

• Gu Q, Pan T, Cheng R, Huang J, Zhang K, Zhang J, Yang Y, Cheng P, Liu Q, Shen H. Macular vascular and photoreceptor changes for diabetic macular edema at early stage. Sci Rep. 2024 Sep 4;14(1):20544. doi: 10.1038/s41598-024-71286-6. PMID 39232012
• Kim JT, Lee MW. Longitudinal changes in each retinal layer thickness in patients with moderate or more severe diabetic retinopathy taking calcium dobesilate. PLoS One. 2025 Jun 4;20(6):e0325655. doi: 10.1371/journal.pone.0325655. eCollection 2025. PMID 40465771
• Aldakhil S, Challa N, Alhoshan SA, Abohaimed F, Alnasser BN, Almuhawas HA, AlObaisi S, Alrasheed SH. Quantitative Analysis of Early Retinal Changes and OCT Parameters in Diabetic Subjects with and Without Retinopathy. Diagnostics (Basel). 2025 Feb 13;15(4):451. doi: 10.3390/diagnostics15040451. PMID 40002602
• Kalaw FGP, Sharma P, Walker E, Borooah S. Differences in macular thickness associated with peripheral retinal vessel whitening in diabetic patients. Sci Rep. 2024 Aug 27;14(1):19881. doi: 10.1038/s41598-024-68839-0. PMID 39191790
• Endo H, Kase S, Tanaka H, Takahashi M, Katsuta S, Suzuki Y, Fujii M, Ishida S, Kase M. Factors based on optical coherence tomography correlated with vision impairment in diabetic patients. Sci Rep. 2021 Feb 4;11(1):3004. doi: 10.1038/s41598-021-82334-w. PMID 33542264
• Shah J, Tan B, Wong D, Abdul Gani NFB, Hu Q, Liu X, Chua J. Evaluation of thickness of individual macular retinal layers in diabetic eyes from optical coherence tomography. Sci Rep. 2024 Aug 2;14(1):17909. doi: 10.1038/s41598-024-68552-y. PMID 39095380

Identifiers

NCT: NCT07232225 · OCT DME

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗