Joanna G. Hollingsworth

Correlation of the appearance of the keratoconic cornea in vivo by confocal microscopy and in vitro by light microscopy.

Objective: To compare morphologic features of keratoconus as observed in vivo with a slit scanning confocal microscope and in vitro using light microscopy. Methods: Slit scanning confocal microscopy (CM) was used to evaluate the central cornea of 29 keratoconic subjects (mean age, 31 ± 10 years; range, 16-49). Light microscopy (LM) examination was performed on 2 of the keratoconic corneas post-keratoplasty. Results: With CM, the epithelium appeared more abnormal with increasing severity of keratoconus. In severe disease, the epithelium displayed the following characteristics: superficial cells were elongated and spindle shaped, wing cell nuclei were larger and more irregularly spaced, and basal cells were flattened. These findings were confirmed by LM. Images obtained using CM revealed disruption to Bowmans layer and the occasional presence of epithelial cells and stromal keratocytes. This was shown with LM to be due to breaks in Bowmans layer. Stromal haze and hyperreflectivity observed with CM corresponded with apical scarring seen on slit-lamp biomicroscopy. Hyperreflective keratocyte nuclei observed with CM are thought to indicate the presence of fibroblastic cells seen with LM. Increasing levels of haze detected with CM were found with LM to be due to fibroblast accumulation and irregular collagen fibers. Descemets membrane appeared normal with both CM and LM. Evidence of endothelial cell elongation was apparent in 1 subject with CM. Conclusions: The current study confirms the application of CM for assessing morphologic alterations to the epithelium, Bowmans layer, and stroma in keratoconus. Many of the tissue changes observed with CM could be reconciled with observations made using LM. This work provides a framework against which tissue changes in keratoconus can be studied in a clinical context in vivo using CM.

In vivo corneal confocal microscopy in keratoconus

Purpose:  To evaluate the corneas of keratoconic subjects using in vivo confocal microscopy.

Observations of banding patterns (Vogt striae) in keratoconus: a confocal microscopy study.

Purpose: To investigate Vogt striae in keratoconus using confocal microscopy. Methods: The central cornea of 51 eyes of 29 subjects with keratoconus was observed using a slit-lamp biomicroscope, slit-scanning confocal microscope (TOMEY Confoscan 1), and corneal topographer (EyeSys 2000). Results: Alternating dark and light bands were seen in the stromal images of 23 eyes examined. The bands corresponded with the appearance of Vogt striae on slit-lamp biomicroscopy examination. Bands were found most commonly in the posterior stroma. Posterior bands varied in width, ran mainly in a nearly vertical direction, and appeared to run a straight course through individual image frames. Keratocyte nuclei were located in between the bands. Posterior keratocyte density was unaffected by the presence of bands. Nerve fibers appeared to run a straight course through the bands. When present, bands in the anterior stroma showed greater variability in width and direction within a single frame. Bands were only present in the anterior stroma in more severe levels of keratoconus. The difference in banding pattern noted between the anterior and posterior stroma parallels the known collagen fiber arrangement in the anterior and posterior stroma. Conclusions: The bands apparent on confocal microscopy of the stroma of the keratoconic cornea correspond with Vogt striae on slit-lamp microscopy. It appears that these bands (and hence Vogt striae) represent collagen lamellae under stress. The stress pattern appears to radiate from the center of the cone and is consistent with the direction of striae when viewed with the confocal microscope.

Confocal microscopy of Thygeson's superficial punctate keratopathy

Purpose.To describe the changes seen with the confocal microscope in Thygesons superficial punctate keratopathy (TSPK).Methods.Confocal microscopy was performed on six patients with TSPK presenting to Manchester Royal Eye Hospital from October 1999 to June 2001. Both eyes were examined including th