Corneal sensation and subbasal nerve alterations in patients with herpes simplex keratitis: an in vivo confocal microscopy study.
OBJECTIVE
To study and correlate corneal sensation in patients with herpes simplex keratitis (HSK) with density and morphologic features of subbasal corneal nerves by in vivo confocal microscopy (IVCM).


METHODS
Prospective, cross-sectional, controlled, single-center study.


METHODS
Thirty-one eyes with the diagnosis of acute (n = 7) or chronic (n = 24) HSK and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15).


METHODS
In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmlogie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (> 5.5 cm), mild (> 2.5-5.5 cm), and severe (≤ 2.5 cm) loss of sensation.


METHODS
Changes in corneal nerve density, total nerve number, main nerve trunks, branching, and tortuosity were evaluated after IVCM and were correlated to corneal sensation, disease duration, and number of recurrences.


RESULTS
Herpes simplex keratitis eyes, as compared with controls, demonstrated significant (P < 0.001) decrease in mean nerve density (448.9 ± 409.3 vs. 2258.4 ± 989.0 μm/frame), total nerve number (5.2 ± 4.5 vs. 13.1 ± 3.8), main nerve trunks (2.3 ± 1.6 vs. 4.7 ± 1.2), and nerve branches (3.2 ± 4.3 vs. 9.8 ± 3.3). In contralateral unaffected eyes, mean nerve density (992.7 ± 465.0 μm/frame), total nerve number (7.8 ± 3.3), and branches (4.5 ± 2.3) were decreased significantly as compared with controls (P < 0.002). Reduced nerve density, total nerve count, and main trunks in HSK eyes were correlated significantly with corneal sensation across all subgroups (P < 0.001). Nerve density decreased within days of infection and was correlated to frequency of episodes in patients with HSK (P < 0.02).


CONCLUSIONS
In vivo confocal microscopy revealed that the loss of corneal sensation in HSK correlates strongly with profound diminishment of the subbasal nerve plexus after herpes simplex virus infection. Surprisingly, the contralateral, clinically unaffected eyes also demonstrated a diminishment of the subbasal nerve plexus as compared with normal subjects, revealing bilateral nerve alteration in an apparently unilateral disease.
Hamrah
Pedram
P
Massachusetts Eye & Ear Infirmary, Cornea Service & Ocular Surface Imaging Center, Department of Ophthalmology, Harvard Medical School, Boston, Massachusett 02114, USA. pedram_hamrah@meei.harvard.edu
Cruzat
Andrea
A
Dastjerdi
Mohammad H
MH
Zheng
Lixin
L
Shahatit
Bashar M
BM
Bayhan
Hasan A
HA
Dana
Reza
R
Pavan-Langston
Deborah
D
D000208:Acute Disease; D002908:Chronic Disease; D003315:Cornea / Q000294:innervation* / Q000503:physiopathology*; D003389:Cranial Nerve Diseases / Q000175:diagnosis*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016849:Keratitis, Herpetic / Q000175:diagnosis*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D009412:Nerve Fibers; D009415:Nerve Net; D009882:Ophthalmic Nerve / Q000473:pathology*; D011446:Prospective Studies; D012677:Sensation / Q000502:physiology*; D016037:Single-Blind Method
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