Kenichiro Bessho

Serial Measurements of Higher-Order Aberrations after Blinking in Patients with Dry Eye

PURPOSEnTo study the sequential postblink changes in ocular higher-order aberrations (HOAs) in patients with dry eye.nnnMETHODSnA wavefront sensor was used to measure HOAs sequentially for 30 seconds in 20 eyes of 20 patients with dry eye. The 20 eyes were classified into two groups, with or without superficial punctate keratopathy (SPK) in the central cornea. During the measurement, subjects were required to blink every 10 seconds. The aberration data were analyzed in the central 4-mm diameter for coma-like, spherical-like, and total HOAs up to sixth-order Zernike polynomials. Total HOAs, as well as fluctuation index (FI) and stability index (SI) of the total HOAs over time were compared between the two groups. The sequential changes in coma-like aberration, spherical-like aberration, and total HOAs were also investigated.nnnRESULTSnThe total ocular HOAs were significantly (P = 0.001) greater in dry eyes with central SPK than in dry eyes without central SPK. The sequential pattern of the total ocular HOAs had higher initial and consistently higher values in dry eyes with central SPK, whereas that of dry eyes without central SPK showed consistently lower total HOAs that were similar to the pattern of normal eyes.nnnCONCLUSIONSnIncreased HOAs in dry eye at least partially result from SPK above the optical zone. The low tear volume in dry eye may not cause sequential increases in HOAs after blinking. Sequential measurement of HOAs may be useful for evaluating the sequential changes in optical quality in patients with dry eye.

Macular autofluorescence in eyes with cystoid macula edema, detected with 488 nm-excitation but not with 580 nm-excitation

BackgroundFundus autofluorescence (AF) derives from lipofuscin in the retinal pigment epithelium (RPE). Because lipofuscin is a by-product of phagocytosis of photoreceptors by RPE, AF imaging is expected to describe some functional aspect of the retina. In this study we report distribution of AF in patients showing macular edema.MethodsThree eyes with diabetic macular edema (DME) and 11 with retinal vein occlusion (RVO), associated with macular edema (ME) were examined. ME was determined by standard fundus examination, fluorescein angiography (FA) and optical coherence tomography (OCT). AF was recorded using a Heidelberg confocal scanning laser ophthalmoscope (cSLO) with 488xa0nm laser exciter (488xa0nm-AF), and a conventional Topcon fundus camera with halogen lamp exciter and 580xa0nm band-pass filter (580xa0nm-AF). Color fundus picture, FA image and these two AF images were analyzed by superimposing all images.ResultsAll subjects presented cystoid macular edema (CME) with petaloid pattern hyperfluorescence in FA. In 488xa0nm-AF, all eyes (100%) showed macular autofluorescence of a similar shape to that of the CME in FA. In contrast, in 580xa0nm-AF only one eye (7%) presented this corresponding petaloid-shaped autofluorescence. In all cases, peripheral retinal edemas did not show autofluorescence corresponding to the leakage in FA.ConclusionsIn eyes with CME, analogous hyperautofluorescence to the CME was always observed in 488xa0nm-AF, while it was rarely observed in 580xa0nm-AF. Moreover, this CME hyperautofluorescence was only seen in the macular area. We hypothesize that autofluorescence from CME may be considered as a “pseudo” or “relative” autofluorescence, due to macular stretching following CME that may result in lateral displacement of macular pigments (MPs) and subsequent reduction of MPs density, as MPs block 488xa0nm-AF more intensely than 580xa0nm-AF. Although this phenomenon may not directly indicate change of RPE function, it may be used as a method to assess or track CME non-invasively.

Adaptive Optics Fundus Camera to Examine Localized Changes in the Photoreceptor Layer of the Fovea

PURPOSEnTo examine highly localized photoreceptor disruptions in the fovea by a high-resolution adaptive optics (AO) fundus camera combined with Fourier-domain optical coherence tomography (FD OCT).nnnDESIGNnObservational case series.nnnPARTICIPANTSnThree eyes of 3 patients who showed dark foveal spots by slit-lamp biomicroscopy.nnnMETHODSnThree patients who reported metamorphopsia but showed no changes in the retina in conventional fundus photographs were examined. High-resolution retinal images were obtained with the AO fundus camera and by FD OCT. The images were compared with the findings obtained by standard clinical tests, including Amsler charts and fluorescein angiography (FA).nnnMAIN OUTCOME MEASURESnQuantitative measurements of the area of photoreceptor disruption.nnnRESULTSnSlit-lamp biomicroscopy revealed an irregularly shaped dark spot in the fovea centralis but no changes in FA in the 3 cases. The photoreceptor mosaic was absent in a highly localized area of the fovea in the images obtained by the AO fundus camera, and the photoreceptor outer segment was absent or disturbed at the corresponding area by FD OCT in all 3 cases. The horizontal and vertical sizes of the area of disturbance of the photoreceptor mosaic in the AO images in the 3 eyes were 400x200 microm, 300x120 microm, and 300x200 microm. These sizes were comparable to the photoreceptor outer segment disturbances in the OCT images which were 330x150 microm, 280x100 microm, 200x150 microm, respectively.nnnCONCLUSIONSnLocalized OS disturbances were able to be detected in eyes with a dark foveal spot by AO fundus camera 2-dimensionally and by FD OCT axially. The good correspondence of the sizes of the area of photoreceptor disturbances obtained by AO images to those by FD OCT images indicate that the AO images can be used to evaluate and follow the 2-dimensional area of focal changes of the photoreceptors in the fovea quantitatively.

Intensity analysis of Hartmann-Shack images in cataractous, keratoconic, and normal eyes to investigate light scattering.

PurposeA clinical investigation of novel methods for evaluating light scattering using a Hartmann-Shack aberrometer.MethodsAberrometry was performed on normal eyes (n = 7; patient age, 26.7 ± 2.5 years, mean ± SD), eyes with keratoconus (n = 22; patient age, 26.1 ± 8.1 years), and eyes with cataract (n = 17; patient age, 56.5 ± 16.9 years) using a Hartmann-Shack wavefront aberrometer. We introduced two methods: (1) a contrast method, in which we calculated the inverse of contrast of the local images around 12 spots in a Hartmann-Shack image, and (2) a difference of point spread function (PSF) method, in which we analyzed the difference between the width of the PSF computed with aberration information and the width of the measured PSF, which contains both aberration and light scattering information.ResultsThe inverse contrast in cataractous eyes (5.04 ± 3.06 inverse contrast units) was significantly larger than that in normal eyes (1.57 ± 0.56) or keratoconic eyes (1.83 ± 0.79). The difference of PSF in cataractous eyes (81.8 ± 65.2u2009μm) was also significantly larger than that in normal eyes (9.3 ± 4.3u2009μm) or keratoconic eyes (30.0 ± 20.1u2009μm). The inverse contrast and the difference in the PSF were highly correlated (r = 0.89, P < 0.0001).ConclusionsThe two methods introduced here successfully distinguished cataractous eyes from normal and keratoconic eyes. After the results were analyzed by a discriminant analysis, the separation of the three categories proved to be excellent.u2003Jpn J Ophthalmol 2006;50:323–333

Automated keratoconus detection using height data of anterior and posterior corneal surfaces.

PurposeTo develop a keratoconus detection algorithm using the corneal topographic data of the anterior and posterior corneal surfaces.MethodsTopographic measurements of the cornea were made with a slit-scanning corneal topographer. We examined 120 subjects (165 eyes); keratoconus patients and keratoconus suspect patients comprised the keratoconus group, and post-photorefractive keratectomy patients, with-the-rule astigmatism patients, and controls without disease comprised the nonkeratoconus group. Two variables of the anterior corneal surface, two variables of the posterior corneal surface, and one corneal thickness variable were obtained by applying the Fourier harmonic decomposition formula. By performing a logistic regression analysis with a training set to differentiate the keratoconus group from the nonkeratoconus group, the Fourier-incorporated keratoconus detection Index (FKI) was created. The validity of the FKI was determined by using independent validation sets.ResultsThe FKI distinguished the keratoconus group from the nonkeratoconus group with 96.9% sensitivity and 95.4% specificity in the validation set.ConclusionsA newly developed automated keratoconus classifier can be used to screen keratoconic patients. The index is based on information obtained by Fourier analysis from not only the anterior corneal surface but also from the posterior corneal surface and corneal thickness.u2003Jpn J Ophthalmol 2006;50:409–416

Photoreceptor images of normal eyes and of eyes with macular dystrophy obtained in vivo with an adaptive optics fundus camera

PurposeTo report on images of the human photoreceptor mosaic acquired in vivo with a newly developed, compact adaptive optics (AO) fundus camera.MethodsThe photoreceptors of two normal subjects and a patient with macular dystrophy were examined by using an AO fundus camera equipped with a liquid crystal phase modulator. In the eye with macular dystrophy, the fixation point in the AO images was identified using scanning laser ophthalmoscope (SLO) microperimetric image superimposed on a color fundus photograph.ResultsPhotoreceptor cells were detected as bright dots approximately 4 μm in diameter in normal subjects. In the eye with macular dystrophy, the fixation point was located within the bull’s eye lesion and uniform small whitish spots with irregular patchiness were observed in the AO images of this area. The distance between the small spots was 3–4 μm. In other parts of the bull’s eye retinal lesion, the whitish spots were larger and of different sizes.ConclusionsThe photoreceptor mosaic could be identified in photographs of eyes of normal subjects and an eye with macular dystrophy in vivo by an AO fundus camera. In the eye with macular dystrophy, a relatively uniform photoreceptor mosaic was observed around the fixation point, whereas presumed debris of photoreceptor degradation was observed in the other bull’s eye retinal lesion.

Wavefront analysis of eyes with cataracts in patients with monocular triplopia1

Purpose:u2002 To determine whether wavefront analysis using a Hartmann–Shack (H‐S) aberrometer can reveal the cause of monocular triplopia in eyes with mild cataracts.

Fourier analysis of corneal astigmatic changes following photorefractive keratectomy

The purpose of this study was to evaluate the corneal irregular astigmatism following photorefractive keratectomy (PRK) for myopia. The corneal topography of 30 eyes of 26 patients was measured with the TMS-1 videokeratoscope before and 1 month after PRK. Axial dioptric data were decomposed into four components; A0 (Sphericity), C1 × 2 (Asymmetry), C2 × 2 (Regular astigmatism), and C3 (higherorder irregularity) for the central 3 and 6 mm zone by Fourier series harmonic analysis. Post-operative topographies were divided into those with an irregular and those with a homogeneous pattern, and the Fourier components were compared. In the 6mm zone, A0 was significantly decreased (P < 0.001), and C1 × 2, C2 × 2, and C3 were significantly increased (P = 0.001, 0.005, 0.002, respectively). In the 3mm zone, A0 decreased (P < 0.001) and C1 × 2 increased (P < 0.001) significantly. C1 × 2 was correlated with the post-operative corrected visual acuity (P < 0.001, r = 0.647). The irregular pattern group had a larger C1 × 2 component (P < 0.001). The treatment displacement was not correlated with any component. In conclusion, irregular topography due to intraoperative drift or asymmetrical wound healing may play a more important role in the post-operative corneal optical property than mild treatment displacement.