PMID- 8653527
OWN - NLM
STAT- MEDLINE
DCOM- 19960801
LR  - 20220210
IS  - 1081-597X (Print)
IS  - 1081-597X (Linking)
VI  - 12
IP  - 2
DP  - 1996 Feb
TI  - Mathematical simulation of retinal image contrast after photorefractive 
      keratectomy with a diaphragm mask.
PG  - 248-53
AB  - BACKGROUND: Photorefractive keratectomy (PRK) using a dilating diaphragm mask 
      engraves a delicate three-dimensional staircase pattern into a formerly smooth 
      corneal surface. The created steps are later smoothed by tear film and wound 
      healing processes. The present study investigates, in a mathematical simulation, 
      the effects that such staircase patterns and their smoothing may have on retinal 
      image contrast. METHODS: All simulations are based on the Gullstrand eye model 
      and calculate retinal image contrast from point spread function (PSF) analysis of 
      Gullstrand eyes treated by simulated PRK under various conditions. RESULTS: The 
      simulations indicate that PRK can reduce retinal contrast markedly. The most 
      critical factor for such a reduction is the step height of the ablation pattern. 
      With step heights below 0.4 microns, loss of contrast due to the created 
      staircase pattern is always moderate and should be restored during early wound 
      healing. Complete wound healing may smooth out larger step heights. 
      Micromovements during PRK also can lead to partial loss of retinal image 
      contrast. CONCLUSIONS: Simulation of retinal contrast after PRK shows that step 
      heights below 0.4 microns seem to be acceptable. A minimization of the 
      micromovements during PRK can offset some of the reduction of retinal contrast.
FAU - Ludwig, K
AU  - Ludwig K
AD  - University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany.
FAU - Schaffer, P
AU  - Schaffer P
FAU - Gross, H
AU  - Gross H
FAU - Lasser, T
AU  - Lasser T
FAU - Kampik, A
AU  - Kampik A
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Refract Surg
JT  - Journal of refractive surgery (Thorofare, N.J. : 1995)
JID - 9505927
SB  - IM
MH  - Contrast Sensitivity/*physiology
MH  - Cornea/physiopathology
MH  - Humans
MH  - Lasers, Excimer
MH  - *Models, Theoretical
MH  - Photorefractive Keratectomy/*instrumentation
MH  - Postoperative Complications/*physiopathology
MH  - Pupil/physiology
MH  - Retina/*physiopathology
MH  - Treatment Outcome
MH  - Wound Healing/physiology
EDAT- 1996/02/01 00:00
MHDA- 1996/02/01 00:01
CRDT- 1996/02/01 00:00
PHST- 1996/02/01 00:00 [pubmed]
PHST- 1996/02/01 00:01 [medline]
PHST- 1996/02/01 00:00 [entrez]
AID - 10.3928/1081-597X-19960201-06 [doi]
PST - ppublish
SO  - J Refract Surg. 1996 Feb;12(2):248-53. doi: 10.3928/1081-597X-19960201-06.