M. Bohnke et Br. Masters, LONG-TERM CONTACT-LENS WEAR INDUCES A CORNEAL DEGENERATION WITH MICRODOT DEPOSITS IN THE CORNEAL STROMA, Ophthalmology, 104(11), 1997, pp. 1887-1896
Objective: Confocal in vivo real-time microscopy was applied to study
the corneal morphology in long-term contact lens wearers, Design: In a
cross-sectional study, patients with a history of long-term contact l
ens wear underwent corneal confocal microscopy, The authors investigat
ed 13 patients with a history of up to 26 years of soft contact lens w
ear, 11 patients with a history of up to 25 years of rigid gas permeab
le contact lens wear, and a control group of 29 normal subjects withou
t a history of contact lens wear, Intervention: Scanning slit-confocal
microscopy was performed with a 50x/1.0 NA water immersion objective.
Corneal optical sections were recorded in real time without further d
igital processing and reviewed frame by frame, Main Outcome Measures:
Video frames selected from all corneal layers were evaluated qualitati
vely. The new finding of panstromal microdot deposits was quantitated
in a scoring system ranging from 0 to 4+. Corneal endothelial cell den
sities were counted with the fixed frame technique, Results: Epithelia
l microcystic changes and alterations of endothelial cell morphology w
ere found to a variable extent as described previously. A new finding
was there were highly reflective panstromal microdot deposits in the c
orneal stroma, For this new disease, a scoring system ranging from 0 t
o 4+ was established. In the control group, 0 of 29 patients had strom
al microdot deposits, In the soft contact lens group, 13 of 13 patient
s had panstromal microdot deposits with a mean score of 3.1 (range, 1-
4), and in the hard contact lens group, 11 of 11 had a mean score of 1
.9 (range, 1-4) for corneal microdot deposits.Conclusions: With confoc
al microscopy, a new type of chronic stromal change has been observed
in all subjects with long-term contact lens wear. Because subjects wit
h soft contact lens wear had a more pronounced corneal degeneration th
an did subjects with gas permeable lenses, the authors assume the depo
sits to be induced by chronic hypoxia. The condition of stromal microd
ot degeneration as observed with confocal microscopy may be the early
stage of a significant corneal disease, which eventually may affect la
rge numbers of patients after decades of contact lens wear.