Tear function and ocular surface findings in premature and term babies

Objective To describe the ocular surface and tear function findings in premature and term babies. Design Prospective, case-control study. Participants Forty-eight eyes of 24 premature babies seen at the Department of Ophthalmology of Uludag University School of Medicine, Bursa, Turkey, from March 2002 through September 2002 and 50 eyes of 25 healthy term babies were studied. Intervention The subjects underwent routine ophthalmic examinations; corneal sensitivity measurements; Schirmer test with anesthesia, with and without nasal stimulation; primary Jones test; fluorescein staining of the ocular surface; and conjunctival impression cytology. Main outcome measures Premature and term babies were compared for corneal sensitivity, lacrimal drainage system patency, tear function and ocular surface staining parameters, goblet cell density, and squamous metaplasia grade. The relation of these parameters to the status of the ocular surface was also investigated. Results Mean corneal sensitivity scores were 45±5.0 mm and 55±4.5 mm in the premature and term babies, respectively (P<0.001). Premature babies had a mean corneal fluorescein staining score of 1.5±0.25 points, compared with 0.22±0.28 points in the term babies (P<0.001). The mean Schirmer test scores without and with stimulation were 1.5±2.5 mm and 4.15±2.5 mm in the premature babies, respectively, compared with 15±3.5 mm and 18.75±4.5 mm in the term babies. The intragroup and intergroup Schirmer test scores were statistically significant (P<0.001). The primary Jones test was positive in 20.8% of the eyes in the premature babies, whereas it was positive in 84% of eyes in the term babies. The premature babies with positive primary Jones test results all had corneal epithelial defects or severe superficial punctuate keratopathy. Mean conjunctival impression cytology squamous metaplasia scores were 1.86±1.2 in the premature babies and 0.86±0.47 in the term babies (P<0.001). Mean goblet cell densities were 393±484 cells/mm² and 739±503 cells/mm² in the premature and term babies, respectively (P<0.001). Conclusion Decreased corneal sensitivity, reduced tearing, and lacrimal drainage patency are important determinants of ocular surface disease in premature infants. Premature newborns with low Schirmer test scores and a patent lacrimal system may experience corneal and conjunctival epithelial problems and should be carefully checked for the presence of dry eye complications.