Keratoconus Patients Undergo Retinal Thickness, Optic Disc Changes

Inflammatory conditions may be responsible for retinal, choroidal, and optic disc changes noted in patients with keratoconus.

Keratoconus may be associated with retinal, optic disc, and choroidal changes, which include decreased superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel densities, increased choriocapillaris flow area, and choroidal thickening, according to a study published in Photodiagnosis and Photodynamic Therapy.

Researchers enrolled 22 patients with keratoconus (eyes, 32; mean age, 28.50 years) and 22 age- and sex-matched control individuals (eyes, 22; mean age, 30.63 years) in the study and examined  posterior segment changes between participants. All study participants underwent optical coherence tomography-angiography (OCT-A) imaging and corneal topography.

The OCT-A analysis included SCP, DCP, and outer retinal segmentation. The research team calculated choriocapillaris flow, perifoveal vessel densities of the SCP and DCP,  choriocapillaris flow area, and foveal avascular zone (FAZ) area.

Both SCP and DCP vessel densities were significantly reduced among participants with keratoconus compared with individuals in the control group (P <.001 for both whole image and parafovea). However, choriocapillaris flow area was significantly higher in patients with keratoconus compared with control participants (2.23 vs 2.13 mm2; P =.003). 

KC was known as a non-inflammatory disease until recently; however, in recent years, inflammation has been shown to play an important role in the etiopathogenesis of KC.

The keratoconus cohort had thicker choroidal thickness measurements compared with patients in the control group (324.84 vs 292.17 µm; P =.019) and FAZ area was similar between the 2 groups (0.26 mm2 for both; P =.949). Radial peripapillary capillary inside disc vessel density was significantly lower among individuals with keratoconus compared with the individuals in the control group (P <.001).

“[Keratoconus] was known as a noninflammatory disease until recently; however, in recent years, inflammation has been shown to play an important role in the etiopathogenesis of [keratoconus],” the study authors note. “The inflammatory process promotes changes to the blood supply, cellular components, and chemical environment of the involved area. These structural and functional modifications can result in transient and/or permanent changes to the tissues, both detectable with OCT-A.”

Study limitations include a small sample size and failure to assess the correlation between keratoconus severity and observed vascular changes.

References:

Dogan B, Bozdogan YC, Gedik B, Erol MK, Bulut M, Duman F. Optic disc and retinal vessel densities assessment by optical coherence tomography angiography in patients with keratoconus. Photodiagnosis Photodyn Ther. Published online November 30, 2022. doi:10.1016/j.pdpdt.2022.103218