Efficacy Analysis of Corneal Photo-vitrification (CPV) for Improved Vision of Age-related Macular Degeneration (AMD) Eyes

Purpose: To analyze the safety and efficacy of corneal photovitrification (CPV) for improved visions of age-related macular degeneration (AMD) eyes.

Study Design: Using CPV for improved visions of AMD eyes.

Place and Duration of Study: New Taipei City, Taiwan, and Austin, TX, USA; between April, 2022 and June, 2022.

Methodology: The CPV efficacy is calculated based on the rate equation given by dM/dt=-k(t) M(t), where M(t) is the PCV-treated corneal stroma; and k(t) is the rate coefficient given by an Arrhenius formula, k(t) = A0 exp[−Ea/(RT(t,z)], where t and z are the laser irradiation time and depth of the cornea stroma; Ea is the activation energy and R is the gas constant. The temperature spatial and temporal profiles are given by the numerical solutions of a heat diffusion equation with a volume heating source. Various effective depths including the tissue damage depth, temperature penetration depth and conversion depth, governed by the tissue absorption coefficient, light intensity and dose (or irradiation time), and the related threshold values, are introduced in replacing the conventional penetration depth based on a Beer's law.

Results: The suggested protocol for CPV treatments include: a diode laser at about 2 µm wavelength (with absorption coefficient about 100 cm-1). The laser dose is about 25 J/cm2/spot and irradiation time of 150 ms.

Conclusion: The efficacy of CPV may be predicted/calculated by our modeling based on rate equation and the corneal stroma temperature rise due to laser heating. The preferred retinal locus (PRL) movement observed post-CPV is caused mainly by neuroadaptation.