Ea. Adams et al., EFFECT OF NEODYMIUM-YAG LASER ON SODIUM HYALURONATE IN-VITRO AS A MODEL FOR POSTCAPSULOTOMY INTRAOCULAR-PRESSURE CHANGE, Journal of cataract and refractive surgery, 22(6), 1996, pp. 748-751
Purpose: To define one possible etiology for the rise in intraocular p
ressure (IOP) after neodymium:YAG (Nd:YAG) laser capsulotomy and provi
de information for the continued investigation of this process. Settin
g: Laser Center, Eye and Ear institute, Pittsburgh, Pennsylvania. Meth
ods: Samples of 1% sodium hyaluronate or balanced salt solution (BSS(R
)) (control) were placed in a closed system and exposed to varying amo
unts of Nd:YAG energy delivered by a Coherent YAG laser. This system w
as hydrostatically coupled to a pressure monitor, and changes in press
ure were recorded as a function of time. Results: Average pressure inc
rease was 0.140 mm Hg/mJ of YAG energy in the sodium hyaluronate sampl
es and 0.017 mm Hg/mJ in BSS (P < .01). The relationship between total
energy delivered and maximum pressure recorded for both substances wa
s nearly linear. Further analysis of treated sodium hyaluronate sample
s showed that Nd:YAG energy can produce structural alterations. Conclu
sions: Neodymium:YAG laser energy has a pronounced effect on sodium hy
aluronate that exceeds the thermal effect seen with BSS when the press
ure is monitored in a closed system. These structural changes might co
ntribute to the IOP rise seen clinically.