Faculty Bibliography

PURPOSE/OBJECTIVE:To report a patient who developed a left paracentral stromal scar due to infectious keratitis that occurred after corneal collagen cross-linking (CXL) for progressive keratoconus. The flattening effect of the scar led to an increase in visual acuity. METHODS:The corneal scar and flattening effect on the anterior corneal curvature were assessed by slit-lamp photography, high-resolution Scheimpflug imaging, and corneal confocal microscopy. RESULTS:Three days after CXL, a corneal bacterial infection occurred in the left cornea and was treated with local antibiotics that led to a paracentral scar. Twenty-one days after CXL, a flattening of the anterior curvature of >11.00 diopters was observed. As a consequence, corrected distance visual acuity improved by five lines. CONCLUSIONS:Corneal remodeling may lead to a homogenization of the anterior corneal surface and an increase in visual acuity. Remodeling may not only occur spontaneously following CXL, but also following an event that results in focal corneal scarring, such as corneal infection. In a highly irregular keratoconic cornea, the benefit of the flattening effect of a scar may outweigh the increase in aberrations and light scatter.

PURPOSE/OBJECTIVE:To investigate the elementary temporal properties of electrically evoked percepts in blind patients chronically implanted with an epiretinal prosthesis. METHODS:Nine subjects were presented with isolated stimuli of variable duration and pulse rate. Stimulation amplitude was set to the upper comfortable level and a group of 2 × 2 adjacent electrodes was simultaneously activated. First, subjects were asked to verbally describe their visual perception paying particular attention to the time-course of brightness. Then, in subsequent trials, they described the brightness time dependence using a joystick while auditory feedback of joystick position was provided. RESULTS:All subjects described a bright, well-localized percept at stimulus onset. Only one subject reported such a bright, well-localized visual sensation during an entire 10-second stimulation trial. For the remaining eight subjects, it faded more or less rapidly (in four cases <0.5 second) and was often followed by a percept described as less bright, poorly localized, and having different color. Only initial percepts at stimulation onset seemed bright and localized enough to reconstruct a patterned image. Changing stimulation pulse rate influenced the time course of perception only in some cases but the effect was not systematic. CONCLUSIONS:Percepts differed considerably across subjects, probably because of the considerable variations in the progression and remodeling processes associated with the disease. Appropriate coding of a patterned image under such conditions appears challenging. Further research of the underlying mechanisms of visual perception upon electrical stimulation of the retina is required to optimize stimulation paradigms and to better establish patient selection criteria.

Addressing these business and financial components of research, we believe that including a section on translational vision research especially for refractive surgery will be a welcome addition to the readership of the Journal. Although the section "Translational Science" is new, the Journal has published a number of articles in past years that would have been ideal candidates for such a section. The inaugural Translational Science article in this month's issue is fron Santhiago and colleagues on short-term cell death and inflammation after intracorneal inlay implantation in rabbits. Although not all scientists are in agreement with the promotion of this term, the Journal aims to provide different outlooks and modern usage of translational research in this way to advance the field of refractive surgery.