Topographic steep central islands following excimer laser photorefractive keratectomy (PRK)

Ronald R. Krueger, Peter J. McDonnell

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Background: The purpose of this study is to demonstrate that topographic irregularities in the form of central islands of higher refractive power can be seen following excimer laser refractive surgery. Methods: We reviewed the computerized corneal topographic maps of 35 patients undergoing excimer laser PRK for compound myopic astigmatism or anisometropia from 8/91 to 8/93 at the USC/Doheny Eye Institute. The topographic maps were generated by the Computed Anatomy Corneal Modeling System, and central islands were defined as topographic areas of steepening of at least 3 diopters and 3 mm in diameter. A grading system was developed based on the presence of central islands during the postoperative period as follows: Grade 0: absent, Grade 1: present at 1 week, Grade 2: present at 1 month, Grade 3: present at 3 months. Results: A total of 70%, 50% and 20% of patients had steep central island formation at 1 week, 1 month and 3 months, respectively. In the absence of nitrogen gas blowing, over 64% of patients had grade 2 or 3 central islands (present at 1 month and beyond) in comparison to only 20% when gas blowing was present. In those eyes with grade 2 islands, 80% had loss of best corrected visual acuity at 1 month with improvement of vision at 3 months when the island was no longer present. Conclusion: Visually significant topographic steep central islands may be seen in over 50% of patients at 1 month following excimer laser PRK, and persist at 3 months in up to 24% of patients without nitrogen gas blowing. Loss of best corrected visual acuity or ghosting is associated with island formation, and may prolong visual rehabilitation after excimer laser PRK.

Original languageEnglish (US)
Pages (from-to)230-235
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Jun 23 1994
Externally publishedYes
EventOphthalmic Technologies IV 1994 - Los Angeles, United States
Duration: Jan 23 1994Jan 29 1994

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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