Assessing changes in retina over time following uncomplicated cataract extraction
The effects of cataract surgery are generally evaluated based on improvements in vision, but investigators sought to identify if the structures in the back of the eye were affected as well.
Polish investigators led by Maciej Gawecki, MD, from the Department of Ophthalmology, Specialist Hospital in Chojnice, Chojnice, and the Dobry Wzrok Ophthalmological Clinic, Gdańsk, both in Poland, reported that uncomplicated cataract surgery may not be as simple as it sounds in that the posterior segment of the eye is affected.
The effects of cataract surgery are generally evaluated based on improvements in vision, but they sought to identify if the structures in the back of the eye were affected as well.
Using spectral-domain optical coherence tomography (SD-OCT) and OCT angiography (OCTA), the investigators noted that the surgery can result in increased retinal thickness and volume in the first few postoperative months; they noticed that the thickening then was followed by a spontaneous decline in both parameters in the subsequent months.
The study was conducted in one ophthalmology unit and included 44 patients with no retinal abnormalities, who were followed after a unilateral uncomplicated phacoemulsification procedure. Follow-up evaluations were conducted 2 weeks and 3 and 12 months postoperatively and the following parameters were measured: best corrected visual acuity, central retinal thickness (CRT), average central retinal thickness (CRTA), central retinal volume (cube volume [CV]), vessel density central (VDC), vessel density full (VDF), vessel perfusion central (VPC), and vessel perfusion full (VPF), the authors explained. The effective phacoemulsification time (EPT) of each surgery also was recorded and served as a covariant to evaluation any changes in retinal parameters following surgery.
Forty-four eyes underwent SD-OCT and 17 OCTA.
Retinal changes observed
Dr. Gawecki and coauthors reported finding significant increases in the CRT, CRTA, and CV at each follow-up point compared with the baseline values. The increases occurred during the first 3 postoperative months. The VPF parameter improved and remained stable postoperatively.
No association was found between the EPT and any changes in the CRT, CV, CRTA, VDC, and VPF; however, the EPT had a slight effect on the VDF.
The investigators speculated that an inflammatory reaction may be attributed to the surgery itself and is controlled routinely by topical anti-inflammatory drugs. Typically, the surgery-induced inflammation peaks within a few days postoperatively and then declines over the ensuing 2 to 3 weeks.
In contrast, the current results indicated that variations in retinal parameters were long-standing and, therefore, unlikely to result from a surgery-induced inflammatory process, they explained.
Another theory was that a decrease in intraocular pressure after cataract surgery improved retinal perfusion and increased OCTA parameters; however, no increase in ocular perfusion pressure has ever been reported.
A third hypothesis possibly affecting the vascular improvement after cataract surgery is functional hyperemia, which results from increased light exposure leading to enhanced retinal metabolism, they theorized. The investigators believe this is the most likely scenario in that “increased retinal metabolism involves the consumption of large oxygen and glucose amounts, which triggers the production of vasoactive mediators leading to vasodilation and hyperemia,” they explained, and “this effect should be reflected in an increase in OCTA parameters. According to our results, the improvement in retinal perfusion after cataract surgery is stable and long-standing, which indicates the third mechanism as the most plausible.”
