The aim of this study was to investigate the effect of lubricant eyedrops containing propylene glycol 400 (PEG) and polyethylene glycol (PG) with hydroxypropyl guar (HP-guar) as a gelling agent on the precorneal mucous layer in vivo.
Sixteen New Zealand white rabbits were randomly assigned to 1 of 4 groups. All rabbits received PEG/PG/HP-guar tear products in the right eye. PEG/PG/HP-guar with Polyquad, 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline was placed in the left eyes of animals in each group. All eyedrops were used 4 times a day for 7 days. An additional 8 rabbits were randomly assigned to 1 of 2 groups. One group received PEG/PG/HP-guar products 4 times a day for 7 days (long-term exposure group), and the other group received PEG/PG/HP-guar products 3 times at 5-minute intervals (short-term exposure group). Fifteen minutes after the last drop was administered, each cornea was immediately excised and mucous layer thickness measured by transmission electron microscopy.
Mucous layer thickness was significantly greater in eyes treated with PEG/PG/HP-guar products compared with those treated with 0.1% hyaluronate sodium, 0.5% carboxymethylcellulose, or phosphate-buffered saline (all P values < 0.001). There were no significant differences in mucous layer thickness between PEG/PG/HP-guar products and PEG/PG/HP-guar with Polyquad or in the long- and short-term exposure animals.
This study demonstrates that even a short exposure to PEG/PG/HP-guar tear product increased precorneal mucous layer thickness.
From the *Deparment of Ophthalmology, East-west Neo Medical Center, Kyung Hee University College of Medicine, Seoul, Republic of Korea; †Department of Ophthalmology, Inje University College of Medicine, Sanggye Paik Hospital, Seoul, Korea; ‡Department of Ophthalmology and Visual Science, College of Medicine, The Catholic University of Korea, Seoul, Korea; and §Department of Surgery, Yonsei University College of Medicine, Seoul, Korea.
Received for publication April 28, 2009; revision received October 9, 2009; accepted November 2, 2009.
Supported by a grant of the BumSuk Academic Research Fund of 2008.
None of authors have financial or proprietary interests in any material or method mentioned.
S-W. Moon and J-H. Hwang contributed equally to this work and both should be considered as first authors.
Reprints: Kee-Hyun Nam, Department of Surgery, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemun-Gu, 120-752 Seoul, Korea (e-mail: firstname.lastname@example.org).