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Computed tomographic images and three-dimensional expression of crystalline lens findings from multiple slices of Scheimpflug slit images.

Although the observation of lens changes in clinical examination has been made through a slit lamp microscope under dilated pupil, precise documentation and analysis of lens changes are presently possible through Scheimpflug photographic images. However, the methodology is still unsatisfactory because the image analysis is two dimensional. In order to overcome this disadvantage, the authors aimed at developing a new methodology for obtaining computed tomographic images of the lens. 60 Scheimpflug slit images of a cataractous human lens were taken by an anterior eye segment analysis system as digital data. After the locations of the whole slit images had been matched, reconstruction of the coronal section line images was performed utilizing extracted image information. The total number of reconstructed coronal section images in additional procedures of the image interpolation was 150. Computed tomography of the lens image was made from those 150 images. A whole lens figure was also demonstrated as a moving three dimensional image.

Aged↗

Binocular indirect argon laser photocoagulator.

The binocular indirect argon laser photocoagulator was newly designed to enable visualisation of the entire fundus during panretinal laser photocoagulation and to treat retinal tears immediately after buckling procedures of the sclera. The lamp housing of the binocular ophthalmoscope was remodelled and adjusted so that the laser beam and illuminating light are coaxial after leaving the ophthalmoscope. The blocking filter was permanently fixed in the eye-pieces to lighten the weight of the ophthalmoscope. This new delivery system of the laser beam supplies the clinician with a better view of the whole fundus than the standard slit-lamp delivery system, and may become the ideal method for panretinal photocoagulation in the treatment of diabetic retinopathy and central retinal vein obstruction and for the repair of retinal tears. However, a fine and delicate laser technique in the posterior pole does not suit the function of this new delivery system well. Proper use of photocoagulation therapy by combining the standard and the new delivery system of the laser beam is preferable, depending on the location and nature of the retinal lesions.

Argon↗

Blood velocity measurement in human conjunctival vessels.

The bulbar conjunctiva is one of the few areas in which blood flow in the peripheral vasculature can be directly and noninvasively observed in the human. Although extensive literature exists describing morphological changes which correlate with a variety of systemic diseases in this vasculature, little quantitative data is available on hemodynamics in either normal or abnormal states. The hemodynamic data available are primarily subjective assessments of "low flow." Approaches to place the subjective assessment on more quantitative grounds have usually been based on photographic techniques that have intrinsic inadequacies. The objective of the work reported here was to develop a system capable of providing sequential blood velocity data potentially useful for providing quantitative information on blood flow and its change in the microvessels of the human conjunctiva. The method that has evolved uses a standard Zeiss slit-lamp to image a subject's conjunctival vessels by using a 1-inch Newvicon TV camera with an electronic magnification of 2x. The video image is simultaneously recorded on a video tape recorder (VTR) to an overall system magnification of approximately 4 microm/raster line. The data acquisition phase requires approximately 5 minutes of patient time, whereas the actual determination of blood velocity in individual vessels is done offline through a modification of the dual-slit videodensimetric method. Two independently controllable video cursors are placed axially over the vessel image with the VTR in the still-frame mode. For each consecutive video field, the position of two reference points on the vessel and the position of each cursor relative to these and to each other are encoded into a computer to track the moving image caused by normal eye movement. The computer then determines new cursor coordinates to ensure a constant position within the vessel. The electrical signals obtained for each cursor site and for each video field are cross-correlated to yield the average blood velocity over the sampled time interval. The system has been calibrated in vitro from 0.2 to 2.5 mm/sec, evaluated in experimental animals, and used to measure blood velocity (0.3 to 1.5 mm/sec) in human conjunctival venules with diameters ranging from 20 to 50 microm. At this writing, blood velocity has been recorded during a period of about 3 months in the same vessel of several postmyocardial infarction patients. Thus, the method appears suitable for determining sequential changes in small vessel blood flow in patients over extended periods of time.

Journal Article↗

Light scattering of whole excised human cataractous lenses. Relationships between different light scattering parameters.

The light scattering intensities of 27 cataractous human lenses were obtained as a function of scattering angle. Unpolarized white light (tungsten) and polarized light of Hg lamp at 435.8 and 546.1 nm were used in the I parallel and I+ modes. Selected light scattering parameters such as relative scattering intensities (I45/I0), dissymmetry ratio (I135/I45) and depolarization ratios (I45/I0)+/(I45/I0) parallel were correlated with the age of lens with percent transmission using regression analysis. Excess scattering functions were calculated that quantitatively describe the quality of lens. These excess functions were also correlated with other scattering parameters. A method which can be used to estimate the light intensity that reaches the retina at different scattering angles for a cataractous lens once the back scatter intensity (slit lamp examination) is known is given.

Adult↗

Light scattering of normal human lens. III. Relationship between forward and back scatter of whole excised lenses.

Twenty-three human lenses from age 3-76 years were studied. Lenses obtained 24-36 post-mortem were exposed to monochromatic light (435.8 and 546.1 nm) in the I parallel and I+ modes and to white (tungsten lamp) unpolarized radiation. The light scattering intensities were obtained as a function of scattering angles from 0 to 135 degrees. The scattering intensities in the forward directions are greater than in the back scatter in all modes of illuminations. The age dependence of a number of light scattering parameters such as percent transmission; I theta/Io; dissymmetry and depolarization were obtained using regression analysis. These parameters may serve as standards of normal lenses to which similar parameters of cataractous lenses can be compared. Relationships between back scatter and forward scatter have been established using the regression coefficients. Thus, the light scattering intensity observed in the slit lamp (at 135 degrees back scatter) can be quantitatively related to the light reaching the retina at different angular displacements.

Adolescent↗

Tear meniscus height, lower punctum lacrimale, and the tear lipid layer in normal aging.

PURPOSE: The purposes of this study are to investigate the tear meniscus height (TMH), lipid layer, and critical dimensions of the lower punctum lacrimale (DPL) in normal human subjects over a large age range; and to determine the shape and general characteristics of the lower punctum lacrimale in a normal population. METHODS: TMH and DPL were measured using a graticule set at the eyepiece of a slit lamp biomicroscope (magnification 32x). Lipid layer was assessed by interferometry (Tearscope, Keeler). Only one eye (right) of each subject was assessed. All subjects were normals without any tear-related disorders and/or symptoms. RESULTS: Four hundred forty-four subjects were assessed (268 females, age range, 6-91 years; 176 males, age range, 6-91 years). Mean (+/-standard deviation) TMH in females was 0.19 mm (+/-0.11) and in males was 0.19 mm (+/-0.10). TMH was related to age (x): in females, TMH=0.13+0.0009x (r=0.2393, p<0.001); in males, TMH=0.14+0.0008x (r=0.2492, p<0.001). TMH increased from 0.15 mm (+/-0.06) in the young (<20 years) to 0.21 mm (+/-0.10) in the elderly (>80 years). The punctum was closed in 10.8%, slit shaped in 24.3%, oval in 5.4%, and round in 59.5% of all cases. Mean age and TMH of those presenting with closed puncta was significantly higher than those presenting with open puncta (p<0.001). Mean (+/-standard deviation) area of open puncta was 0.008 mm (+/-0.013) in females and 0.010 mm (+/-0.018) in males. The difference was not significant. Diameter of round puncta was inversely related to age in females (r=-0.4985, n=149, p<0.001) but not within the males. A total of 14.6% of females and 12.5% of males presented with no discernible lipid layer. Lipid layer tended to be thinner in older subjects (one-way analysis of variance, F=6.667, p<0.001). There was no clear relationship between TMH and the lipid layer. CONCLUSIONS: There is a gradual increase in TMH and shift in size and shape of the punctum lacrimale with advancing years. Age-related changes in the lipid layer are expected to reduce tear volume by way of increased evaporation. On balance, it would appear any effects on tear volume by a thinning lipid layer are outweighed by changes in the puncta.

Adolescent↗

Vitreous fluorophotometry: identification of sources of variability.

Slit-lamp vitreous fluorophotometry (VF) has been used by several investigators to document the early breakdown of the blood-ocular barrier. After an injection of fluorescein, levels of fluorescein in the vitreous humor are reported to be elevated in diabetic patients compared with controls even when there is no retinal pathologic condition discernible by angiography or ophthalmoscopy. We have examined the technique of VF in normal persons and have identified several potential sources of error in the determination of vitreous fluorescein levels. Fluorescein in the choroidal circulation significantly influences VF readings taken at the retinal surface and in the posterior vitreous. This effect is modulated by ocular pigmentation, with heavy pigmentation of dark-eyed normals more effectively screening out choroidal fluorescence than the light pigmentation of blue-eyed subjects. Influence of choroidal fluorescein extends toward the midvitreous, and the range of influence is directly related to the slit width of the exciting light. At narrow slit widths the effect is diminished but can never be completely eliminated. Blood fluorescein levels decrease with time, and since choroidal fluorescein contributes to VF values, the time after injection that VF reading are taken is a critical parameter.

Adult↗

Hyphaema due to blunt trauma.

OBJECTIVE: To study the causes, clinical presentation, complications and visual outcome of hyphaema following closed globe injury. DESIGN: Prospective study. PLACE AND DURATION OF STUDY: The study was conducted at the Department of Ophthalmology, Postgraduate Medical Institute, Lady Reading Hospital, Peshawar, Pakistan, from May, 1996 to June 1997. PATIENTS AND METHODS: All cases of hyphaema, due to closed globe injury, were included and history of patients was recorded on a comprehensive proforma designed for this purpose. All cases were admitted for at least 5 days. Ocular examination included checking visual acuity (VA), intraocular pressure (IOP), slit lamp and fundus examination. Patients were treated accordingly and followed up for 90 days. RESULTS: Thirty-six eyes of 36 patients with hyphaema were included in our study. Out of this, 88.89% were males and 11.11% females while 86% were 20 years of age or below. Almost 91.66% presented with primary hyphaema, 44.44% received trauma with stone and 27.77% with tennis ball while playing cricket. Trauma during playing was noted in 66.66% of cases. Almost 62% of cases were having visual acuity in the range of CF to perception of light with good projection. IOP was raised initially in 41.66% cases. Only 33.33% needed surgical intervention. Secondary glaucoma was present in 13.88% and 5.55% had corneal blood staining. Majority of patients (75%) improved to VA range of 6/6 to 6/12 and 19% patients in our study ended up with legal blindness in the affected eyes. CONCLUSION: Traumatic hyphaema is more frequently found among children and young male. Angle recession, traumatic cataract and maculopathy were common co-morbidities. Secondary glaucoma and corneal staining were the main complications. Nearly 1/5th of patients ended up with legal blindness in the affected eyes.

Adolescent↗

Effectiveness of chloroquine and hydroxychloroquine in treating selected patients with sarcoidosis with neurological involvement.

OBJECTIVE: To assess the efficacy of chloroquine (Aralen) phosphate and hydroxychloroquine (Plaquenil) sulfate in the treatment of patients with neurosarcoidosis who either do not respond to corticosteroid therapy or develop unacceptable side effects. DESIGN: Retrospective study. SETTING: Sarcoidosis clinic at a university teaching hospital. PATIENTS: Twelve patients with biopsy-proved sarcoidosis, 6 women and 6 men ranging from 20 to 49 years of age, with neurological involvement. INTERVENTION: Chloroquine phosphate, 250 mg twice daily, or hydroxychloroquine sulfate, 200 mg twice daily, was administered for a period of 6 to 21 months. Patients had regular clinical evaluation, determination of serum and cerebrospinal fluid angiotensin-converting enzyme level, computed tomography or magnetic resonance imaging, chest radiography, lung function testing, and slit-lamp examination of the eyes. RESULTS: Chloroquine or hydroxychloroquine either stabilized symptoms or controlled neurological symptoms in 10 of 12 patients. Two patients failed to respond. Cerebrospinal fluid abnormalities, including lymphocytosis, were seen in 3 patients. Magnetic resonance imaging with gadolinium was most helpful in supporting the diagnosis of sarcoidosis and monitoring the course of the disease. CONCLUSIONS: Chloroquine and hydroxychloroquine are effective in controlling neurological sarcoidosis in those patients who fail to respond to corticosteroids or develop severe side effects. Ocular toxic effects from chloroquine or hydroxychloroquine were not observed.

Adult↗

Late-onset bleb leaks after glaucoma filtering surgery.

OBJECTIVE: To determine the incidence of focal, late-onset, conjunctival bleb leaks after glaucoma filtering surgery. DESIGN: Prospective, cross-sectional analysis. SETTING: Tertiary care outpatient referral center. PATIENTS: Consecutive patients who underwent glaucoma filtering surgery prior to June 1996 presenting for evaluation from September 2,1996, through November 15,1996. Five hundred twenty-five eyes of 525 consecutive patients were enrolled in the study. INTERVENTION: Bleb height (elevated or flat), area (diffuse or localized), and wall thickness (thin, thick, or encapsulated) were classified. Each bleb was tested for focal leakage using a moistened fluorescein strip, cobalt blue illumination, and slit-lamp biomicroscopy. Diffuse transconjunctival aqueous flow did not qualify as a focal leak. MAIN OUTCOME MEASURE: Seidel-positive aqueous leakage. RESULTS: Bleb leakage occurred in 14 eyes following trabeculectomy (mitomycin C treatment, 10 eyes; 5-fluorouracil treatment, 3 eyes; no antifibrosis agent, 1 eye) and in 1 eye following combined cataract and glaucoma surgery with adjunctive mitomycin C therapy. Bleb leakage occurred more frequently in eyes that received mitomycin C (10 [3.7%] of 273 eyes) than 5-fluorouracil (3 [1.4%] of 213 eyes) or no antifibrosis agent (1 [2.6%] of 39 eyes), using Kaplan-Meier estimates (P=.008, log-rank test). Conjunctival blebs were significantly thinner after trabeculectomy with mitomycin C than with 5-fluorouracil (P=.001). Bleb wall thickness was greater following combined cataract and glaucoma surgery than following trabeculectomy alone (P=.008). Age (P=.84), sex (P=.68), race (P=.77), duration of mitomycin C exposure (P=.62), number of antiglaucoma medications (P=.16), and total 5-fluorouracil dose (P=.85) were not associated with late-onset leaks. CONCLUSIONS: The risk of late-onset focal bleb leakage increases following trabeculectomy with mitomycin C therapy. Late leakage after combined cataract and glaucoma surgery is infrequent.

Adolescent↗

Tear production after unilateral removal of the main lacrimal gland in squirrel monkeys.

OBJECTIVE: To study the effects of lacrimal gland removal on basal and reflex tear production and on the ocular surface in the squirrel monkey. METHODS: Unilateral main lacrimal gland removal in 6 squirrel monkeys was followed by Schirmer testing, slit-lamp examination with fluorescein, and collection of basal and reflex (stimulated) tears for analysis of tear protein spectra between 0 and 20 kd, as well as histological evaluation. RESULTS: Schirmer test results showed an 80% decrease in basal tears and a 90% decrease in reflex tears during week 1, and a 32.2% and 33.3% decrease, respectively, at week 20 after surgery, compared with the contralateral control side. However, no gross abnormalities or fluorescein staining were seen in 5 of the 6 monkeys, and the conjunctival surfaces remained normal. The main and accessory lacrimal glands appeared to secrete similar types of proteins. No histological changes were seen in corneal, conjunctival, or eyelid tissues 20 weeks after surgery. CONCLUSIONS: Tears from accessory lacrimal glands were sufficient to maintain a stable tear layer on the cornea, suggesting that so-called basal tear flow is made up of fluid from both main and accessory lacrimal glands and that decreased tear production by the main lacrimal gland is not a causative factor in keratoconjunctivitis sicca. CLINICAL RELEVANCE: This study shows that total removal of the main lacrimal gland does not in itself lead to keratoconjunctivitis sicca. However, the nature of neural control of the accessory glands is not yet clear.

Animals↗

Prevention of experimental allergic uveitis. Treatment and methotrexate.

These experiments were undertaken to determine if methotrexate therapy, initiated after immunization, could prevent the development of experimental allergic uveitis. Strain 13 guinea pigs were immunized with Strain 13 guinea pig retina-uvea extract that had been emulsified in Freund complete adjuvant. Some were treated with methotrexate twice a week until the 21st day. Each week, all of their eyes were examined with a slit-lamp. At the end of the study, some were skin tested, and the sera of selected animals were tested by immunodiffusion for antibody. The eyes of certain groups were examined histologically. Results show methotrexate prevented the development of this type of uveitis, even when therapy was initiated seven days after immunization. The disease did not appear after therapy was stopped. Methotrexate also inhibited the development of skin sensitivity and antibody to retina-uvea antigen.

Animals↗

New Tyndall photometer.

An instrument is described that can accurately measure delicate changes in the Tyndall phenomenon in the anterior chamber of the eye. An important feature is its use of an external light source and its simple adaptation to the slit lamp.

Humans↗

Multiple-slit illumination of the optic disc.

A modification to a photo slit-lamp illuminator adds detail to the human optic disc surface by projecting onto it a pattern of fine parallel lines. These stripes curve as they traverse the disc, and its surface contour is revealed. Application of this technique may improve the reliability of methods used to quantitate disc topography.

Evaluation Studies as Topic↗

Studies on retinal blood flow. II. Diabetic retinopathy.

Diabetic patients grouped according to the evolutive stages of their retinal involvement were examined by a direct method for estimation of segmental retinal blood flow by slit-lamp fluorophotometry. Initial stages of retinal involvement in diabetes, in which the only alteration is a breakdown of the blood-retinal barrier, show values of segmental blood flow that are within normal limits. Patients with a minimal background retinopathy show a slight increase in retinal blood flow, whereas an highly significant increase of segmental blood flow is observed in the more advanced stages of background retinopathy with maculopathy. In general, a good correlation is apparent between the progressions of diabetic background retinopathy and increase in retinal blood flow. On the other hand, patients with proliferative retinopathy show lower values of retinal blood flow, which are attributable to a marked decrease in arterial diameter.

Blood Circulation↗

Endothelial cell population changes of human cornea during life.

A photo slit lamp was used to obtain color, specular reflex, high magnification photographs of the corneal endothelium of subjects ranging in age from 3 to 88 years. Multiple areas of the cornea were examined to determine the endothelial cell population. No appreciable difference in cell density was found between the right and left eyes of the subjects nor between male and female subjects of similar age. Apparent defects in the endothelial cell coverage of Descemets membrane were found in subjects as young as 20 years of age and with increased frequency in older age groups. These defects were at times associated with variations in endothelial cell populations between the central and peripheral cornea. The average corneal cell population fell from nearly 1 million cells in the first years of life to about one third that number by the eight decade of life.

Adolescent↗

Subepithelial infiltrates: a probable sign of corneal transplant rejection.

A previously undescribed slit-lamp manifestation of a probable corneal transplant rejection reaction was found in 22 patients among 145 who underwent penetrating keratoplasty during a two-year period. The reaction consisted of subepithelial infiltrates that were located only in the donor tissue; were without associated conjunctivitis; and that occurred six weeks to 21 months postoperatively, either alone or in association with epithelial and/or endothelial rejection; and that responded well to topical corticosteroid treatment. In one case, the subepithelial infiltrates preceded a severe endothelial rejection by only a few days. The lesions are a warning that all is not well and that corticosteroid therapy should be instituted or increased.

Administration, Topical↗

Epithelialization of the anterior chamber: clinical investigation with the specular microscope.

Four patients, each of whom had had an uncomplicated cataract extraction, were examined because of an apparent epithelialization of the anterior chamber. In each instance, the diagnosis was later verified histopathologically. The involved eye was photographed with the clinical specular microscope and the endothelial photomicrographs were analyzed. It was noted that considerable endothelial cell loss had occurred, as evidence by the larger size of the remaining cells. Endothelial cells were present but they were grossly abnormal well below the demarcation line visible with the slit-lamp biomicroscope. These in vivo observations support the thesis that damage to the corneal endothelium is a necessary factor for epithelial invasion of the anterior chamber.

Aged↗