Posterior capsule opacification in eyes with diabetes mellitus
Posterior capsule opacification (PCO) is a frequent and important complication noticed in diabetics undergoing cataract surgery, however, few studies have examined the prevalence of PCO in diabetic versus non-diabetic patients. Therefore, the authors performed a study exploring the long-term effect of diabetes on the incidence of PCO and here they highlight their findings.
There is paucity of available literature that prospectively evaluates PCO development after a single-piece hydrophobic acrylic IOL implantation in diabetic versus non-diabetic eyes on a long-term basis. We designed a study to compare the degree of PCO after cataract surgery between age-matched diabetic and non-diabetic patients.
In a prospective, observational case-control study, subjects with a history of diabetes mellitus (DM) were assigned to Group A (n = 75 eyes). The presence of diabetes mellitus was defined as glycosylated haemoglobin (Hb A1c) levels of 6% or more, use of diabetic medication (oral hypoglycemic agents, insulin injection or diet restriction), or a physician's diagnosis of diabetes. The retinal specialist classified and confirmed the findings.
Observation procedures
PCO image interpretation and analysis
All the digital images of posterior capsule was captured using a digital camera (Nikon, Tokyo, Japan) mounted on a slit lamp (Nikon photo slit-lamp FS-3V) and analysed for PCO using the POCO system. The POCO system is a texture-based analysis of digital photographic images.
The area of interest was defined as that part of the posterior capsule lying inside the rhexis or the edge of the lens optic if the rhexis lay off the implant.
Primary observations:
The primary observations were a comparison of the median percentage area of PCO within the anterior capsulorhexis in Groups A and B using POCO software. An assessment was made to gauge whether the anterior capsule on the IOL optic (total on and part on cover over the IOL optic) had any influence on the development of PCO.
The eye was considered to have total cover if the non-overlap of the anterior capsule on the IOL optic was equal to or less than 2 clock hours. The eye was considered to have partial cover if the non-overlap of the anterior capsule on the IOL optic was equal to or greater than 10 clock hours.
The number of eyes that required Nd:YAG laser capsulotomy was also compared between the two groups.
Secondary observations:
Within Group A, the impact that the duration of diabetes (number of years diabetes was present at the time of surgery) had on the development of PCO at 4 years was assessed. The influence of the severity of retinopathy on the development of PCO at 4 years was then evaluated.
The patients returned for postoperative follow-up visits at 1 month, 1 year and 4 years. At every subsequent follow-up visit, with a widely dilated pupil.
