Waldir Neira

Selective Changes in Human Corneal Sensation Associated with Herpes Simplex Virus Keratitis

PURPOSE To determine corneal sensitivity to selective mechanical, chemical, and thermal (heat and cold) stimulation in patients with a history of herpes simplex virus (HSV) keratitis. METHODS Corneal sensitivity to different modalities of stimulus was determined in both eyes of 16 patients with unilateral HSV keratitis diagnosed 1 to 12 months before the study. On slit lamp examination, 13 HSV-affected eyes showed corneal scarring or opacities, and three had no signs of previous keratitis. Corneal sensitivity was determined with the Belmonte gas esthesiometer. Mechanical, chemical, heat, and cold stimuli were applied on the central cornea. Eyes from 10 healthy subjects served as controls. RESULTS In all control and contralateral eyes, selective mechanical, chemical, heat, and cold stimulation evoked sensations of subjective intensity proportional to the magnitude of the applied stimulus. In one HSV patient, the affected cornea was unresponsive to all types of stimuli, four lost only corneal sensitivity to mechanical stimulation, and three lost only sensitivity to heat. Mechanical (P<0.005) and heat (P<0.05) thresholds were raised in HSV eyes, whereas thresholds for CO2 were not modified. Also, HSV subjects identified poorly the intensity of mechanical, chemical, and heat stimuli, whereas sensitivity to cold stimulation was unaffected. CONCLUSIONS In eyes that had had HSV keratitis, corneal sensitivity to mechanical forces and heat was significantly impaired, suggesting that axonal damage and/or altered expression of membrane ion channels involved in transduction and membrane excitability affects primarily the mechano- and polymodal nociceptor terminals. Corneal cold-sensitive terminals remain largely unaffected.

In vivo confocal microscopy study of climatic droplet keratopathy

Sir, Climatic droplet keratopathy (CDK) is a corneal degenerative disease characterized by its progressive opacity because of accumulation of globular deposits in Bowmans layer (BL) and anterior stroma (AS), as well as abnormal corneal sensitivity.1, 2 We report herein for the first time the study of three patients each with different grades of CDK using in vivo confocal microscopy (iVCM), a technique that has allowed the measurement of normal and pathological corneal components.3, 4, 5 Table 1, Figures 1 and ​and22 summarize the corneal abnormalities found in these patients. Cochet-Bonnet aesthesiometry (CBA) demonstrated a decrease of the mechanical sensitivity of the cornea in eyes with grade II and III CDK. Grade I CDK was characterized by incipient changes in the BL and AS but normal sub-basal and stromal nerve plexus. Grade II CDK showed hyper-reflectivity and globular non-reflective deposits in the BL and AS. In grade III, the AS showed fibrosis with increment of diffused hyper-reflective deposits and large non-reflective deposits. Concomitant to these changes, there was an increased number of dendritic cells (DC) at the peripheral cornea and limbus, but their role in the progression of CDK needs further studies. No abnormalities were found in the rest of the stroma and endothelium.​endothelium. Figure 1 In vivo confocal laser scanning microscopy images. BL: (a) Grade 1: dot-like hyper-reflective deposits in the central cornea. (b) Grade 2: increased density of the deposits. (c) Grade 3: confluent hyper-reflective deposits. Sub-basal nerves: (d) Grade ... Figure 2 In vivo confocal laser scanning microscopy images. Deposits at the peripheral cornea: (a) Grade 1: reflective punctiform or dot-like deposits. (b) Grade 2: hyper-reflective punctate and homogeneous round globular non-reflective deposits. (c) Grade 3: ... Table 1 Abnormalities found in corneas of CDK eyes according to biomicroscopic grade of the disease Although we were unable to study sub-epithelial nerves because they occupied the same area of the deposits in CDK, we found that the early changes in CDK did not affect the sub-basal and stromal nerves, but the progression of the disease lead to a significant density decrease of sub-basal nerves, and some structural changes in stromal nerves, such as uneven thickness and irregular configuration, that might be responsible for corneal hyposensitivity found in advanced stages of CDK. In a recent study, Patel et al5 showed that sub-basal nerve tortuosity but not mean total sub-basal nerve density varied with age in normal individuals. The loss of corneal sensation could not be attributed to the age of our patients as we have previously found in a case–control study that corneal sensation was related to CDK grades and not to the age of individuals.2

Long-term outcome of central toxic keratopathy after photorefractive keratectomy.

Purpose: To describe long-term postoperative results of 5 eyes that had central toxic keratopathy after photorefractive keratectomy (PRK). Method: In a period of 2 months, 74 eyes were subjected to refractive surgery (21 by PRK and 53 by laser in situ keratomileusis) in 2006. Laser ablations were performed with a VISX S4 (VISX, Santa Ana, CA) excimer laser. Five eyes of 5 different patients in the PRK group experienced a corneal stromal thinning associated with a central opacification (haze), hyperopic shift, and central striae in the first postoperative week. Follow-up examinations were at 1 month and at 2, 6, and 12 months and included uncorrected visual acuity, best spectacle–corrected visual acuity (BCVA), manifest refraction, biomicroscopy, and ultrasound pachymetry. At the last follow-up, confocal microscopy was performed in 3 eyes. Results: Corneal thickness measured by ultrasound pachymetry at the first month postoperatively showed an unexpected stromal thinning of 48 ± 39 μm (range, 19–116 μm) compared with the expected postoperative value. At the last postoperative follow-up, corneal thickness had gained 44 ± 22 μm (range, 20–80 μm) compared with the thickness obtained at 1 month. Uncorrected visual acuity, BCVA, haze, and corneal thickness improved in the first postoperative months and stabilized after 6 months. Conclusions: Central toxic keratopathy is not related to laser in situ keratomileusis (LASIK) only. The presence of 5 cases after PRK in a short period (2 months) associated with a period of simultaneous change of both postoperative medications and postoperative bandage lens practice suggests a link with an unknown pharmacological response leading to stromal dehydration.

Dystrophia Helsinglandica - corneal morphology, topography and sensitivity in a hereditary corneal disease with recurrent erosive episodes

Purpose:  The aim of this study was to describe the morphology, corneal topography and sensitivity in individuals with Dystrophia Helsinglandica. This autosomal dominant corneal disease is characterized by recurrent corneal erosive episodes and progressive subepithelial fibrosis not significantly affecting visual acuity.

Reply to the Letter to the Editor: “Sudden Onset of Illness While Driving a Vehicle”

Doctors Hitosugi, Motozawa, and Tokudome raise some questions concerning the methodology and conclusions drawn in our recent article (Tervo et al. 2008). We have already (Tervo et al. 2009) clarified our approach and conclusions in a response to a letter by Dr. Alvarez (2009). However, some further comments might help the fellow investigators to understand our study. Hitosugi et al. (2009) consider that the rate of fatal motor vehicle accidents (FMVA) due to a disease attack (DA) is quite high in our study. However, in another independent Finnish study (Rainio et al. 2007) the rate was essentially the same because the accidents were investigated in the same way. There are several reasons for the higher percentage of DAs in the Finnish accident investigation material compared to, for example, Japanese studies (Motozawa et al. 2008). As stated Hitosugi et al., in many countries accidents that follow disease attacks or incapacity to steer the vehicle are listed as sudden natural deaths disregarding to possible accident-related injuries that may or may not be present. We did not exclude these accidents and do not recommend that to be done elsewhere either. If a vehicle remains unsteered it presents an immense and uncontrolled danger for other passengers and road users. In this regard our definition is not obscure because we include such accidents, which—according to our understanding, and in agreement with Hitosugi et al.—throws a challenge not only to medical control of fitness to drive but also to safety features in cars. The Finnish investigation method is not based only on autopsy data, although all drivers who die in FMVAs are autopsied by a specialist in forensic medicine. This is not common in all countries. Restricting the DAs only to those that are detectable by an autopsy would lead to underestimation of DA-related FMVAs. In Finland the investigation team collects the available

Atopic dermatitis is a risk factor for intracorneal ring segment extrusion.

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