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Cataract surgery linked to changes in choroidal thickness, study finds
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Cataract surgery was associated with changes in choroidal thickness, with axial length and IOP being critical in evaluating those changes, according to a study.
“The choroid may be involved in the pathogenesis of various ocular diseases,” the study authors said. “It has been suggested that cataract surgery is associated with the onset of AMD.”
The prospective study included 100 eyes of 100 patients with a mean age of 72.5 years and no other ocular disease who underwent cataract surgery. A control group included 20 eyes of 20 age-matched subjects.
Using enhanced-depth imaging optical coherence tomography, investigators evaluated changes over time in corrected distance visual acuity (CDVA), IOP, axial length and choroidal thickness preoperatively.
IOP in the study group decreased significantly at 3 weeks, 3 months and 6 months postoperatively.
Choroidal thickness increased significantly in the foveal and inferior regions for the duration of follow-up. It increased in the nasal region at 3 days, 1 week and 6 months, in the temporal region at 1 week and in the superior region at 6 months. The changes correlated negatively with early postoperative changes in IOP. Changes in choroidal thickness had a negative correlation with axial length in all regions.
Age, CDVA, preoperative IOP and surgical time correlated insignificantly with changes in choroidal thickness.
Mean IOP and choroidal thickness remained unchanged in the control group, the authors said.
Disclosure: The study authors report no relevant financial disclosures.
Perspective
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Amar Agarwal, MS, FRCS, FRCOphth
The preoperative and postoperative clinical evaluations were done methodically. However, the optical coherence tomography (OCT) technical aspects should have been detailed more, so that it can be repeated by the readers. Enhanced-depth imaging OCT has the ability to delineate the choroid by depth enhancement and thereby is more advantageous than conventional spectral-domain OCT, where the wavelength is not long enough to penetrate deep into the choroid. Imaging the entire choroid has been nearly impossible until the introduction of EDI OCT due to the attenuating effects of the retinal pigment epithelium and outer retina. Also, the dense vascular structure of the choroid created light scattering, which interfered with OCT imaging of the choroid.
There have been few reports on the nature of choroidal thickness by OCT in the recent past. Margolis and Spaide found a statistically significant correlation with age and choroidal thickness, in which the choroid thinned with age. Age-related choroidal atrophy is a choroidal condition identified by EDI OCT. Focal choroidal excavation is another entity detected by the OCT evaluation of choroid. EDI OCT has opened the new spectrum of examining the highly vascular structure, which can remove the limitations of conventional imaging system.
The authors noted that postoperative choroidal thickness significantly increased at the foveal and inferior regions throughout follow-up. One limitation is that they mentioned relative choroidal thinning that happened in the nasal and inferior regions but did not discuss it in the results. The grades of cataract in the included eyes were not mentioned. We know that signal transmission is one main factor that affects the OCT output and it is dependent on the grades of cataract. Overall, the study has shown an important observation of fine changes in choroidal thickness after cataract surgery that may affect the onset of age-related macular degeneration.
References
Margolis R, Spaide RF. A pilot study of enhanced depth imaging optical coherence tomography of the choroid in normal eyes. Am J Ophthalmol. 2009;147:811-815.
Margolis R, Mukkamala SK, Jampol LM, et al. The expanded spectrum of focal choroidal excavation. Arch Ophthalmol. 2011;129:1320-1325.
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