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Kartik S. Kumar, Merrill Stass-Isern, Prabhu Parimi, Timothy Lindquist, Ryan Pine; Determination of Intraocular Pressure During Retinopathy of Prematurity Examinations. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1508.
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Recent studies in premature neonates have demonstrated the development of small retinal hemorrhages after the retinopathy of prematurity exam. The aim of this study is to investigate the intraocular pressures of premature infants at various points during the retinopathy of prematurity exam in order to understand the effect of the mechanical forces during the exam.
18 unique patients and 36 eyes were examined after informed consent was obtained from the parental guardian. Intraocular pressures were measured after instillation of tetracaine with a Reichert ® tonopen prior to insertion of the speculum, after insertion of the speculum, during scleral depression, and after completion of scleral depression.
36 eyes were included in the study. The average intraocular pressure of 30 eyes prior to insertion of the speculum was 35.9 mm Hg (pressures could not be obtained in 6 eyes due to infant size). The average intraocular pressure of the 36 eyes was 32.9 mm Hg after insertion of the wire speculum. The average intraocular pressure of the 36 eyes was 77.7 mm Hg during scleral depression. The average intraocular pressure of the 36 eyes was 27.3 mm Hg after completion of the examination with the speculum still in place. No evidence of retinal hemorrhages were noted during the study.
Although no infants had evidence of retinal hemorrhages during the study, the intraocular pressures during the retinopathy of prematurity exam provided insight into the biomechanical effects of the exam. An interesting finding was the relative decrease in intraocular pressure post scleral depression. This may indicate a possible compression-decompression mechanism created by exam. Additionally, the pressures greater than 70 mm of Hg achieved during scleral depression would be enough to impede perfusion of the central retinal artery. Therefore great care should be taken during the exam. This concept should be considered during the use of cryotherapy as scleral depression during this procedure would likely elevate intraocular pressures above the perfusion pressures for a more extended period of time than with laser therapy. Furthermore, it should be noted that the measurement of intraocular pressures in infants may be elevated simply because the infants are crying or agitated. However, further studies should be performed in older patients to check intraocular pressures after the insertion of an eye speculum. If the insertion of the speculum itself causes a change in intraocular pressure, great care should be used, especially in traumatic situations.
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