Evaluation of Tear Osmolarity Changes After Photorefractive Keratectomy.
OBJECTIVE
To assess tear film stability, ocular surface disease index (OSDI) score, Schirmer test value, tear film breakup time (TBUT), and tear osmolarity after photorefractive keratectomy (PRK).


METHODS
We enrolled 50 eyes from 25 patients who were PRK candidates (15 men, 10 women). The mean age was 31.9 ± 4.5 years. Dry eye severity was evaluated using OSDI questionnaire, TBUT, Schirmer test, and tear osmolarity preoperatively and in each postoperative follow-up visit during the 4-month follow-up period.


RESULTS
Tear osmolarity changed from 302 ± 5.9 mOsm/L preoperatively to 308.8 ± 5.8 mOsm/L (P < 0.0001) and 304.1 ± 9.4 mOsm/L (P = 0.40) after 2 and 4 months, respectively. Schirmer test did not change significantly 4 months after PRK (P = 0.410). TBUT decreased significantly after 2 months and did not return to its preoperative value after 4 months. Subjective complaints measured by OSDI score, improved after 4 months compared with the preoperative level.


CONCLUSIONS
Although dry eye tests (Schirmer, TBUT, and tear osmolarity) are abnormal 2 months after PRK, they returned to preoperative values after 4 months. We can conclude that post-PRK dry eye is a transient complication which will last less than 4 months with regular use of topical lubricants.
Ophthalmology Research Center, Department of Ophthalmology, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Amir H
AH
Beheshtnejad
Hesam
H
Hashemian
Abbas M
AM
Kermanshahani
Alireza
A
Mahmoudi
Mohammad K
MK
Johari
D000328:Adult; D015352:Dry Eye Syndromes / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000378:metabolism / Q000601:surgery*; D009994:Osmolar Concentration; D018903:Photorefractive Keratectomy; D011795:Surveys and Questionnaires; D013666:Tears / Q000737:chemistry*; D055815:Young Adult