RESUMO
AIM: To investigate the impact of multifocal gas permeable contact lens (MFGPCL) in various add power and distance/near area allocation on short-term changes of choroidal thickness (ChT), axial length (AL), and retinal defocus profile in young adults. METHODS: Seventeen young adults (2 males and 15 females; age 23.17±4.48y) were randomly assigned to wear two designs binocularly with a one-week washout period in between. Total of four MFGPCL designs were assessed. All designs were distance-center that varied in two add power (+1.50 and 3.00 D) and/or two distance zone (DZ) diameters (1.50 and 3.00 mm; design A: DZ 1.5/add 3.0, B: DZ 1.5/add 1.5, C: DZ 3.0/add 3.0, D: DZ 3.0/add 1.5). ChT, AL, and peripheral refraction data were collected on each subject at baseline, on days 1 and 7 of MFGPCL daily wear. ChT was assessed in four quadrants using a spectral-domain optical coherence tomography. RESULTS: AL was shortened by -26±44 µm with lens C, -18±27 µm with lens D, -13±29 µm with lens A, and -8±30 µm with lens B (all P<0.05). A significant overall increase in ChT was observed with all 4 designs (lens A: +6±6 µm, B: +3±7 µm, C: +8±7 µm, and D: +8±7 µm). Temporal and superior choroid exhibited more choroidal thickening associated with MFGPCL. All designs induced significant relative peripheral myopia (RPM) beyond the central 20° across the horizontal meridian in both nasal and temporal fields (P<0.05). CONCLUSION: MFGPCLs show a significant influence on ChT and AL, which are associated with significant increase in RPM after short-term wear. The reliability and feasibility of quantifying short-term changes in ChT support its use as a promising marker for the long-term efficacy of myopia-controlling treatments.
RESUMO
PURPOSE: To examine the regional distribution of choroidal thickness (ChT) and the diurnal variation in ChT and axial length (AL) over a wide range of myopic refractive error. METHODS: ChT was measured in thirty-four healthy young adults (age mean ± SD: 25.2 ± 2.8, range: 18-35 years) using spectral-domain optical coherence tomography and AL using an IOL-Master 500. Participants were divided into three refractive groups: emmetropes, myopes, and high myopes. We evaluated ChT in macular (foveal, parafovea, and perifovea) and peripheral regions (6-mm from the foveal pit) in four quadrants (superior, temporal, inferior, and nasal). To assess the diurnal variation, three measurement sessions of ChT and AL were taken at 8 AM, 12 PM, 4 PM. RESULTS: ChT thins progressively towards the periphery. Superior and nasal quadrants exhibited the thickest (277 ± 73 µm) and thinnest (218 ± 89 µm) choroid, respectively. Higher myopic eyes showed an overall thinner choroid (237 ± 48 µm) compared to myopic eyes (264 ± 78 µm) (P < 0.05). Higher myopes exhibited a significant choroidal thinning in all quadrants except in the temporal quadrant (all p < 0.05). Both ChT and AL underwent a significant diurnal variation (p < 0.05). The ChT and AL diurnal variation amplitudes in higher myopes were significantly reduced (ChT: 14.6 ± 11, AL: 14.5 ± 13 µm), compared to those in emmetropes (ChT: 21.4 ± 15, AL: 21.3 ± 8.5 µm) and myopes (ChT: 19 ± 17, AL: 19 ± 9.7 µm). Diurnal variation amplitude in ChT did not differ significantly across quadrants and choroidal eccentricity regions (p > 0.05). CONCLUSION: ChT distribution varies based on quadrant and eccentricity; superior choroid exhibited the thickest, and nasal showed the thinnest choroid. Higher myopes experience a reduced diurnal variation in ChT and AL.
