Cataracts are a leading cause of blindness worldwide and are notably prevalent among individuals with diabetes.1 Diabetes significantly increases the risk of cataract formation due to chronic hyperglycemia, which alters the metabolic and structural integrity of the lens. Studies show that approximately 20% of all cataract surgeries are performed on diabetic patients, emphasizing the strong association between the two conditions. Effective diabetes management and routine eye examinations are crucial in reducing the incidence of cataracts and preserving vision2. Additionally, diabetic individuals are at a heightened risk of developing diabetic retinopathy (DR), a chronic condition resulting from prolonged exposure to elevated blood glucose levels. DR is characterized by vascular damage and neurodegeneration in the retina. One of its earliest clinical signs is the presence of microaneurysms—localized outpouchings in the capillaries—marking the onset of non-proliferative diabetic retinopathy (NPDR)3. Early detection through regular screening is vital, as DR can progress to advanced stages leading to irreversible vision loss. A significant concern in diabetic patients undergoing cataract surgery is the risk of postoperative macular edema (PME), characterized by fluid accumulation and thickening of the macula. This condition is more prevalent in diabetic individuals due to their compromised retinal vasculature and ongoing inflammatory processes. Phacoemulsification, the standard technique for cataract removal, can induce macular changes that are particularly pronounced in diabetic patients4. Optical coherence tomography (OCT), a high-resolution imaging modality, plays a key role in assessing these changes. OCT provides accurate, reproducible measurements of macular thickness, allowing for early detection of PME and timely intervention5.In non-diabetic patients, phacoemulsification typically causes a mild and transient increase in central macular thickness (CMT), peaking around one month post-surgery and resolving within six months. This increase is usually subclinical, without affecting visual acuity. Importantly, it does not typically result in cystoid macular edema (CME), a more serious condition involving fluid-filled cystic spaces in the retina. However, in diabetic patients—even those without clinical signs of retinopathy—the increase in CMT is often more significant. This response is likely due to underlying microvascular abnormalities, such as subclinical inflammation and compromised vascular integrity, which heighten sensitivity to surgical trauma6-7.Notably, the extent of postoperative macular changes in diabetic patients varies depending on the duration of diabetes and the presence or severity of DR. Patients with longer disease duration or early signs of DR often exhibit more pronounced changes in CMT and retinal vasculature, including alterations in the foveal avascular zone (FAZ) and vascular density.8,9 Poor glycemic control further exacerbates these changes. Despite these structural alterations, diabetic patients without retinopathy generally achieve visual outcomes comparable to those of non-diabetic individuals. These findings highlight the importance of personalized perioperative care that includes systemic glycemic control, regular OCT monitoring, and individualized risk assessment.10-13 This tailored approach enhances postoperative recovery and minimizes complications, ultimately preserving vision and improving surgical outcomes for diabetic patients.

AIM

To assess macular thickness after phacoemulsification     by optical coherence tomography in diabetics and non-diabetics.

This study was designed as a prospective observational hospital-based study conducted in the Department of Ophthalmology at Mahatma Gandhi Medical College & Hospital, Jaipur. The research was initiated following formal approval from both the Institute’s Scientific Research Committee and the Institute’s Ethical Committee. The study spanned a period of 18 months, from April 2023 to September 2024. The inclusion criteria comprised patients diagnosed with senile cataracts who were also known cases of type II diabetes with mild to moderate non-proliferative diabetic retinopathy (NPDR). Only those patients without any pre-existing macular edema, defined by a macular thickness of less than 280 microns on Optical Coherence Tomography (OCT), were included. Furthermore, eligible participants had no history of prior laser treatment and underwent uneventful cataract surgery. Patients with a history of previous ocular surgery, prior episodes of uveitis, or any ocular pathology that could affect visual acuity—such as glaucoma—were excluded. Additional exclusion criteria included any present or past retinal or macular disease beyond mild to moderate NPDR, the presence of proliferative diabetic retinopathy (PDR), and systemic illnesses other than diabetes, such as hypertension, asthma, tuberculosis, or cardiac disease. Patients using topical or systemic medications known to influence retinal thickness were also excluded from the study. The final sample size for the study was determined based on the hospital’s patient flow and selection criteria, ensuring adequate statistical power for reliable analysis.

Sample Size:

All the patients who presented to the Department of Ophthalmology, Mahatma Gandhi Medical College & Hospital, Jaipur from April 2023 to September 2024 (18 Months), fulfilling inclusion criteria were included in the study.

Table 1:demographic data of the patients is as follows:

The table presents a comparison of demographic and clinical characteristics between diabetic and non-diabetic groups. The mean age of diabetic participants was 67.26 ± 4.63 years, while that of non-diabetic individuals was 66.98 ± 5.15 years, with a p-value of 0.12, indicating no significant difference. The male-to-female ratio was similar in both groups (53:47 for diabetics and 55:45 for non-diabetics), as was the left-to-right eye distribution (52:48 vs. 51:49). The mean HbA1c level was higher in diabetics (7.37 ± 0.86) compared to non-diabetics (6.74 ± 0.67), though this difference was not statistically significant (p = 0.098). The duration of diabetes in diabetic patients averaged 11.68 years. Among diabetics, 25 individuals were on insulin, and 100 were on oral hypoglycemic agents (OHA).

Table 2: Table showing overall macular thickness in diabetic and non-diabetic patients undergoing phacoemulsification.

Diabetic patients exhibit significantly greater retinal thickening across central, parafoveal, and perifoveal regions following phacoemulsification, particularly in the central fovea, perifovea inferior, and temporal areas. This highlights their increased risk for postoperative macular edema due to underlying microvascular dysfunction and inflammation. Close OCT monitoring, individualized risk assessment, and timely use of anti-inflammatory or anti-VEGF therapies are essential to optimize visual outcomes in diabetic patients post-surgery.

Diabetic patients consistently exhibit greater macular thickness than non-diabetic individuals before and after phacoemulsification, with the most pronounced differences observed in the parafoveal and perifoveal regions. This baseline disparity, likely due to subclinical diabetic macular edema (DME) or increased vascular permeability, becomes more evident postoperatively, especially on Day 30. While both groups show a transient increase in macular thickness following surgery, diabetic patients experience a more significant and prolonged response. Regions such as the parafovea temporal and perifovea inferior are particularly affected, suggesting regional susceptibility in diabetic retinas. Although central foveal thickness increases in both groups post-surgery, the change is more pronounced and resolves more slowly in diabetics, indicating delayed inflammatory resolution. By Day 90, non-diabetics show near-baseline recovery, while diabetic patients still demonstrate elevated thickness values in several regions. This prolonged retinal thickening in diabetics highlights their increased risk for postoperative complications such as clinically significant macular edema (CSME). Importantly, 12% of diabetics developed macular edema compared to just 4% of non-diabetics at three months. These findings underscore the need for enhanced pre- and postoperative care in diabetic patients, including routine OCT monitoring and tailored anti-inflammatory or anti-VEGF therapies, to detect early changes, prevent macular complications, and preserve visual function.

Over the past decade, two key surgical advancements have transformed the landscape of cataract surgery, offering patients improved outcomes and a higher standard of care. Among these, phacoemulsification has emerged as the gold standard, setting a benchmark for safety, precision, and efficiency[55].Phacoemulsification utilizes ultrasound technology to break up the cloudy lens into smaller fragments, which are then aspirated through a small incision. Compared to conventional extracapsular cataract extraction methods, this minimally invasive method dramatically lowers the risk of complications14.

Phacoemulsification cataract surgery has revolutionized patient care by using smaller incisions that minimize tissue trauma, promote faster healing, and reduce infection risk. Advances in surgical technology, such as intraoperative biometry and real-time monitoring, have improved the precision of intraocular lens placement, resulting in better visual outcomes and shorter recovery times. These innovations have also significantly decreased complication rates, including vitreous loss, posterior capsular rupture, and endophthalmitis.15 Enhanced surgical tools and refined techniques contribute to safer, more predictable procedures, improving patient comfort and reducing dependence on spectacles. Optical Coherence Tomography (OCT) reveals that phacoemulsification impacts macular thickness in both diabetic and non-diabetic patients, with diabetic status and retinopathy influencing the degree of postoperative macular changes. Overall, phacoemulsification remains the gold standard in cataract surgery, offering improved safety, efficacy, and patient satisfaction. Phacoemulsification cataract surgery is associated with transient changes in macular thickness, particularly in diabetic patients.16 Studies have shown that central macular thickness (CMT) significantly increases in diabetic eyes within the first few weeks post-surgery, peaking around four weeks and gradually returning to baseline by 12 weeks. This pattern, also observed in our study, suggests that the thickening is mainly due to mild surgical inflammation rather than permanent damage. Non-diabetic patients may experience subclinical increases in macular thickness, but these changes are generally less pronounced and not clinically significant. Importantly, preexisting diabetic macular edema can influence surgical outcomes, but well-managed diabetes reduces the risk of worsening macular edema after surgery.

Cystoid macular edema (CME), a complication occurring in approximately 1–2% of cases, results from fluid accumulation due to inflammation-induced breakdown of the blood-retinal barrier.17 It typically manifests around four weeks postoperatively, although onset can be delayed, especially in diabetic patients. Early detection through Optical Coherence Tomography (OCT) is essential for timely intervention with anti-inflammatory or anti-VEGF therapies, preventing long-term vision loss18. While cataract surgery may trigger or exacerbate macular edema, other conditions such as diabetic retinopathy, retinal vein occlusion, uveitis, and age-related macular degeneration also contribute to macular thickening.

OCT is a non-invasive imaging technology that provides high-resolution, cross-sectional images of retinal layers, enabling detailed assessment of macular thickness and identification of edema. This tool is crucial for monitoring subtle postoperative changes, particularly in high-risk diabetic patients19. However, variability in OCT criteria for defining clinically significant CME complicates comparisons across studies, underscoring the need for standardized diagnostic protocols.20 Factors such as patient age, severity of diabetic retinopathy, and preexisting macular edema influence postoperative macular changes. Older patients, in particular, are more susceptible to transient thickening, possibly due to increased vulnerability to surgical light-induced inflammation.

Despite these macular changes, most studies, including ours, show that the increased macular thickness post-phacoemulsification is transient and does not adversely affect visual acuity or functional outcomes in the short term21. However, the relatively short follow-up period in many studies, including ours, limits understanding of long-term effects. Since CME can develop months to a year after surgery, extended monitoring is recommended to identify delayed complications and optimize management, especially in diabetic patients. Overall, OCT-guided surveillance enhances early detection and treatment of macular changes, helping to preserve vision and improve postoperative outcomes in cataract surgery patients22.

Optical coherence tomography (OCT) is a valuable, non-invasive tool for monitoring macular thickness and detecting early postoperative changes, especially in diabetic patients. While uncomplicated cataract surgery rarely causes significant macular thickening in non-diabetics, diabetics remain at higher risk for CME. Baseline OCT measurements are essential for tracking subtle postoperative changes and guiding timely intervention. Clinicians should maintain close follow-up in diabetic patients to prevent vision-threatening complications. Despite a small sample size, the study's findings align with previous research, supporting their clinical relevance.

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