Glistening formation in an AcrySof lens initiated by spinodal decomposition of the polymer network by temperature change

PURPOSE

To examine the effect of temperature change on the structural alteration and glistening formation in an AcrySof intraocular lens (IOL).

SETTING

Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Kobe, Japan.

METHODS

The equilibrium water content of a Wagon-Wheel-packaged AcrySof IOL was determined at various temperatures by the gravimetrical method. Alterations in the microscopic structure of the lens were analyzed in situ with a reflecting microscope without staining, while the temperature of the lens was changed at different rates.

RESULTS

Microvacuoles of 1.0 to 20.0 microm formed in the bulk of a swollen AcrySof IOL as the temperature decreased. The morphology of the vacuoles was similar to that of glistening particles observed in vivo. The size and density of the glistening-like vacuoles varied depending on the magnitude and rate of the temperature decrease. The glistening-like vacuoles were imprinted in the bulk of the IOL during the preceding cooling process in aqueous humor.

CONCLUSIONS

Glistenings formed in the bulk of an AcrySof IOL as the medium temperature decreased. The mechanism may involve spinodal decomposition of the swollen polymer network, which initiates the formation of microvacuoles consisting of water and loosely packed network chains.

Visual and tear function improvement after superficial phototherapeutic keratectomy (PTK) for mid-stromal corneal scarring

PURPOSE

To study the changes in visual and tear film function following superficial excimer laser phototherapeutic keratectomy in patients with mid-stromal corneal scars.

METHODS

Fourteen eyes of 14 patients with mid-stromal corneal scars seen at the Department of Ophthalmology at Kobe Kaisei Hospital underwent superficial phototherapeutic keratectomy (PTK). The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film break-up time (BUT), Schrimer test and tear film lipid layer interferometry. Thirty eyes of 15 normal control subjects were also studied. The patients and the control subjects were compared for pre-PTK tear function parameters and tear film lipid layer interferometry grade. The alterations in these parameters within 6 months following PTK were also determined.

RESULTS

Visual improvement was achieved in 12 eyes (86%). A hyperopic shift was observed in all eyes. The average pre-PTK corneal sensitivity and tear film BUT were lower in patients compared with control subjects before PTK. Tear film lipid layer interferometry grades were also higher in the patients than the controls before PTK. All these parameters improved gradually and significantly after PTK. Schirmer test results did not show any significant alterations after PTK.

CONCLUSION

We conclude that PTK is an effective means of treating corneal scars and attaining visual improvement, even in cases with deeper corneal involvement, and may obviate the need for corneal transplantation. Simultaneous improvements in corneal sensitivity and tear film stability suggest favourable effects of PTK on the ocular surface.

Ocular surface changes after excimer laser phototherapeutic keratectomy

PURPOSE

To study the ocular surface disorder in patients with Avellino, granular, and lattice dystrophy, band keratopathy, and corneal leukoma before and after excimer laser phototherapeutic keratectomy.

DESIGN

A prospective case-controlled study.

PARTICIPANTS

A total of 45 eyes of 33 patients with superficial corneal opacities seen at Kobe Kaisei Hospital, Department of Ophthalmology, and 40 eyes of 20 normal control subjects were studied.

INTERVENTION

The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film break up time (BUT), Schirmer test, tear film lipid layer interferometry, and conjunctival impression cytology.

MAIN OUTCOME MEASURES

The patients and the control subjects were compared for prephototherapeutic keratectomy (PTK) tear function parameters, tear film lipid layer interferometry grade, goblet cell density, and conjunctival squamous metaplasia grade. Alterations of these parameters within 3 months after PTK were also looked for.

RESULTS

The average pre-PTK corneal sensitivity and tear film break up time were lower in patients compared with control subjects before PTK. Tear film lipid layer interferometry grade and conjunctival squamous metaplasia grades were higher in the patients than the controls before PTK. All these parameters improved gradually and significantly after PTK. Goblet cell density was significantly lower in the patients compared with controls before PTK. Schirmer test results and goblet cell density did not show any significant alterations after PTK.

CONCLUSIONS

Concurrent improvements in corneal sensitivity, tear film break up time, lipid layer interference grades, and conjunctival squamous metaplasia grades all point to the favorable effects of PTK on the ocular surface by improving the stability of the tear film and ocular surface health through attainment of a regular corneal surface and probably inducing qualitatively/quantitatively better mucin production by a healthier epithelium after PTK.

Optical and atomic force microscopy of an explanted AcrySof intraocular lens with glistenings

PURPOSE

To assess the surface morphology and cause of glistenings in an explanted AcrySof intraocular lens (IOL).

SETTING

Shakai Hoken Kobe Central Hospital, Kobe, Japan.

METHODS

A 63-year-old Japanese man had implantation of an AcrySof IOL in the capsular bag. One month postoperatively, he had a neodymium:YAG laser capsulotomy for posterior capsule opacification, which changed the IOL's position in the capsular bag. A few months later, the patient developed disabling night glare from intralenticular glistenings and progressive hyperopic refractive error. The IOL was explanted and then analyzed by optical microscopy and atomic force microscopy (AFM). Laboratory analysis of control AcrySof IOLs kept in a balanced salt solution at steady room and body temperature for 2 months was also performed to evaluate the cause of the glistenings observed clinically.

RESULTS

Optical microscopy showed that the explanted AcrySof IOL had several microvacuoles; no abnormalities were observed in the control AcrySof IOLs before or after folding at the room and body temperatures. The AFM analysis showed a significant change in the surface morphology of the explanted IOL, including vacuolar formations in the posterior surface as well as numerous anterior surface irregularities. No microvacuoles or surface morphology alterations were observed in the control AcrySof IOLs by AFM analysis.

CONCLUSIONS

The glistenings in the explanted AcrySof IOL were likely caused by temperature changes and not mechanical stress from folding.

Ocular surface disease in atopic dermatitis

PURPOSE

To describe the ocular surface disorders of 362 patients with severe active atopic dermatitis (AD) treated in the Ophthalmology Department of Kobe University Hospital and Kobe Rosai Hospital Eye Clinics during the period 1994-1996.

METHODS

Routine ophthalmic examinations as well as tear film break-up time (BUT) and Schirmer tests were carried out.

RESULTS

Lid eczema (65.7%), atopic keratoconjunctivitis, and superficial punctate keratopathy (67.5%) were the dominant ocular diseases in these patients. Tear function tests showed a BUT value of less than 10 seconds in 62.4% of the eyes and a Schirmer test value of less than 5 mm in 56.2% of the eyes.

CONCLUSIONS

A careful examination of the ocular surface is essential in treating AD patients. We also suggest that the ocular surface disorders in AD may be due to allergic reactions and disorders in tear film quantity or quality.

Impression cytology in atopic dermatitis

PURPOSE

This study aimed to describe the ocular surface disorder in patients with atopic dermatitis (AD).

DESIGN

A prospective case-controlled study.

PARTICIPANTS

A total of 44 patients with active AD seen at Kobe University School of Medicine, Department of Ophthalmology, during 1994 through 1996 and 22 normal control subjects were studied.

INTERVENTION

The subjects underwent routine ophthalmic examinations, tear film break-up time (BUT), Schirmer test, and conjunctival impression cytology.

MAIN OUTCOME MEASURES

Patients and control subjects were compared for tear function parameters, goblet cell density, and conjunctival squamous metaplasia grade. The relation of duration and recurrences of AD to the ocular surface disorder also was looked for.

RESULTS

The duration of atopic disease ranged from 18 to 32 years (mean, 22.8 years). The average for exacerbations was 4.5 times. Chronic allergic conjunctivitis with superficial punctate keratitis was the most frequent clinical presentation. The BUT and Schirmer test values were significantly lower in patients with AD compared with those of the control subjects. Impression cytology showed goblet cell loss and conjunctival squamous metaplasia, both of which related to the number of recurrences of AD rather than the duration of disease. Facial atopy and allergic keratoconjunctivitis (AKC) related to the metaplasia of the ocular surface (P < 0.001). Patients with reduced goblet cell density also showed low BUT levels (P < 0.001).

CONCLUSION

Ocular surface disorder of AD characterized by goblet cell loss and conjunctival squamous metaplasia seemed to evolve independently of the duration of disease but worsen with increased number of flare-ups. Direct epithelial damage by the allergic reaction, disorder of tear quality, and quantity may be important in the genesis of the atopic ocular surface disease.

IgG-kappa extramedullary plasmacytoma of the conjunctiva and orbit

Images

Epithelial transformation of the corneal endothelium in forceps birth-injury-associated keratopathy

Using light and electron microscopy, we studied four keratectomy specimens obtained by penetrating keratoplasty from four patients (ages 33-54 years; mean age: 43 years old) who had clinical evidence of Descemet's folds and bullous keratopathy after ruptures in Descemet's membrane after forceps injury at birth. Histopathologically, three patients showed the typical features of forceps birth injury: Descemet's membrane at the margin of the rupture was folded and assumed a scroll-shape configuration. The fourth patient showed clusters of proliferated endothelial cells at the site of two ruptures, and from one site of the ruptures, these cells invaded into Descemet's membrane, forming a new basement membrane. Transmission electron microscopy revealed that these proliferated cells were epithelial-like cells characterized by desmosomal junctions, basal lamina, numerous microvilli, and 8-nm cytoplasmic filaments. The epithelial transformation of the corneal endothelium was identified in cases of posterior polymorphous dystrophy and assumed to be specific for this entity. The findings in our fourth patient represent the first documentation of epithelial-like cells on the posterior corneal surface in forceps birth-injury-associated keratopathy. Our results suggest that epithelial transformation may be a nonspecific reaction of the young cornea to various stimuli.

Late histopathological findings of neodymium:YAG laser iridotomies in humans

We studied three sector iridectomy specimens from three patients who had undergone neodymium:YAG (Nd:YAG) laser iridotomies 3 to 5 years earlier for treatment of imminent angle closure glaucoma. The specimens were obtained during cataract extraction and were examined by light and transmission electron microscopy. In all iris specimens, the edges of the iridotomy sites consisted of loosely arranged melanocytes, fibrocytes, and vessels. In the iris stroma, there were numerous pigment-laden cells. The iris vessels appeared to be intact; there were no fibrinous aggregates, no inflammatory response or scarring, nor any signs of proliferation of the iris pigment epithelium. Our findings suggest that in humans, iris wound healing after Nd:YAG laser iridotomy occurs without induction of fibrous scars or proliferation of the iris pigment epithelium. This indicates that there is no tendency toward late closure of the iridotomy sites.

Precapsular layer of the anterior lens capsule in early pseudoexfoliation syndrome

We examined a possible correlation between clinical signs of early pseudoexfoliation (PSX) syndrome related to pigment dispersion and iris stroma atrophy and morphological alterations of the lens capsule. 63 anterior lens capsules (30 PSX suspects, 3 pre-PSX, 10 PSX, 20 controls) were studied by transmission and immuno-electron microscopy (TEM). In 20 PSX suspect and 3 pre-PSX capsulotomy specimens, TEM revealed a precapsular layer (0.1-11 microns in thickness) composed of microfibrils, amorphous material, and granular inclusions. The incidence of this fibrillar layer was significantly higher (p = 0.001) in PSX suspect and pre-PSX eyes than in controls (5 positive). Ultrastructural and immunohistochemical similarities of the fibrillar surface network in PSX suspect and typical PSX specimens indicate that the precapsular layer may represent a precursor of PSX. The beginning PSX process in the eye is obviously indicated by certain clinical signs.

Lamellar excimer laser keratoplasty: reproducible photoablation of corneal tissue. A laboratory study

We examined the depth of ablation of the recipient bed with different counts of oscillations of excimer laser beam, to determine the correlation between planned and real depth. The ablation rate per oscillation was tested preoperatively by blackened photographic paper of defined thickness and thus was calculated to be 5 microns. Forty pig eyes were used for the first study. Each eight eyes were ablated in the planned depth 100 microns, 200 microns, 300 microns, 400 microns and 500 microns. The corneal thickness was measured with an ultrasonic pachymeter before and after the procedure. The depth measured after the photoablation was 99.4 +/- 36.4 microns for 100 microns planned depth, 186.7 +/- 55.3 microns for 200 microns, 298.4 +/- 68.5 microns for 300 microns, 373.9 +/- 65.7 microns for 400 microns and 480.1 +/- 59.3 microns for 500 microns. Comparing the depth measured after the photoablation to planned depth, there was a significant correlation (correlation coefficient: R = 0.93; p < 0.0001). Five other corneas trephinated from pig cadaver eyes were ablated from the endothelial side to the desired thickness (100 to 500 microns) of lamellar graft. In a second step a donor mask was placed onto the cornea and a laser light spot was led until perforating on all sides. The lamellar keratoplasty was completed by suturing the corneal graft into the bed. Macroscopic and microscopic examination of sutured eyes after fixation showed a good fit of wound margins and stromal interface. These results indicate that excimer laser is useful for reproducible corneal photoablation in lamellar keratoplasty.

[Retinal ganglion cell topography during prenatal development]

A fundamental feature of the human visual system is nonuniform distribution of ganglion cells across the retinal surface. In adults, the density of ganglion cells peaks around the fovea and declines sharply towards the periphery, whereas in fetal retina it does not. In the fetal retina, the retinotopic map is dominated by nonuniform expansion and/or ganglion cell death. We examined how the numbers and distributions change according to the horizontal eccentricity from the foveola, using toluidine blue stained vertical sections of the human fetal retina (gestational age 32W and 40W). The vertical section of the fovea showed almost similar density at 32 weeks, 40 weeks and in adults. This fact suggested that the fundamental structure of the fovea is already established at 32W. In the nasal retina, the cellular density was higher than that in the temporal half at 32W, then markedly decreased at 40W and in adults. We assume that in the nasal retina, it is impossible to account for the cell decrease only with nonuniform expansion and that even after 32W ganglion cell death occurs. On the other hand, in the mid-temporal retina, the cellular density was almost similar at 32W, 40W and in adults. It suggested that in the mid-temporal retina, the topography is already established at 32W. In the peripheral temporal retina, the cellular density was relatively high at 32W and decreased at 40W and in adults. In this area, the topography is still changing. We assume that in the fetal retina, retinotopic map is dominated by several factors and the dominant factor differs according to stage and retinal area.

[Two cases of idiopathic preretinal macular fibrosis in children]

We report herein the findings in two patients less than 15 years old with the diagnosis of idiopathic preretinal macular fibrosis, a disorder found primarily in the older population. Only a few reports have discussed idiopathic preretinal macular fibrosis in children and its pathogenesis is still unknown. One is a 10-year-old boy and the other is a 14-year-old girl who visited our hospital with a chief complaint of blurred vision in their right eyes. Epiretinal membranes were recognized on the macular region of their right eyes. Since there was no causative factors, a diagnosis of idiopathic preretinal macular fibrosis was made. They were conservatively followed up. The vision of the boy once worsened but improved spontaneously and remained stable for three years. Because the vision of the girl worsened rapidly, vitreous surgery was performed to remove the epiretinal membrane, resulting in poor vision. It was suggested that this disorder in children should be followed up conservatively and the indication of vitreous surgery should be carefully determined.

[Reepithelialization of keratolens in the wound healing process following epikeratophakia in rabbits]

Most of the complications of epikeratophakia are minor and can be treated successfully. However, approximately 5 to 10% of cases of epikeratophakia result in removal of keratolenses mainly because of the failure to reepithelialize or chronic epithelial defects. In this study, in order to solve this problem we investigated the process of reepithelialization of epikeratophakia in rabbits. Epikeratophakia was performed on rabbit corneas using cryolathed keratolens. Ten, 16, 45, 63 and 90 days after the operation, corneas were excised, labeled with 3H-thymidine and examined histologically using light and electron microscope and autoradiography. 10 to 16 days after the operation, keratolenses were reepithelialized with a very thin epithelium of one or two layers. Epithelium thickened gradually, but was still thinner than normal controls at day 90. At days 10 and 16, basal cells of the epithelium showed high activity of 3H-thymidine incorporation, suggesting active proliferation. After that the proliferating activity decreased gradually and was no longer seen at day 90. Electron microscopic examination revealed no desmosomes or interdigitation between epithelial cells and poorly developed hemidesmosomes between basal cells and basement membrane at day 10, immediately after reepithelialization. At day 90, the epithelium over the keratolens showed areas where the basement membrane was irregular and extensively interrupted. These results indicated that in epikeratophakia, reepithelialization, recovery of epithelial thickness, formation of differentiated desmosomes or hemidesmosomes and normalization of ultrastructural abnormalities took longer than reepithelialization of usual epithelial defects. These results may explain the reason for of clinical problems of chronic epithelial defects or failure of reepithelialization in epikeratophakia. It was suggested that one of the factors causing delayed reepithelialization in epikeratophakia might be the cryolathing process of the keratolenses.

[Keratocyte activity in wound healing process following epikeratophakia in rabbits]

Epikeratophakia is a refractive surgery for the correction of aphakia, high myopia and keratoconus. Although many clinical studies of epikeratophakia have been performed, its wound healing process is not well understood. In the present study, we investigated keratocyte activities, particularly cell proliferation and collagen synthesis activity, during wound healing following epikeratophakia in rabbit corneas. Ten, 16, 28, 45, 63 and 90 days after the operation, corneas were excised, labeled with either 3H-thymidine (10 microCi/ml) or 3H-proline (10 microCi/ml) in DME for 4 hours and examined histologically, and by autoradiography. Ten days after the operation, almost no cells were seen in the keratolens except for a few keratocytes which had migrated to the edge of the keratolens. At days 16 and 28, keratocytes in the keratolens and in the host stroma near the junction between the host and the keratolens incorporated 3H-thymidine, suggesting active proliferation. The proliferating activity was no longer seen at days 45, 63 and 90. At day 90, almost complete repopulation with keratocytes was observed. Keratocytes in the keratolens and in the host stroma beneath the keratolens showed higher activity of 3H-proline incorporation than those in the control from day 16 through day 90 with the highest activity at day 28.

[Contributory factors for glaucomatous disc cupping. 4. Generalized expansion type and localized type]

It is widely recognized that there are two types progressive disc cupping in glaucoma. One of them is the localized type (L type) in which the cupping extends to a certain direction and the other is the generalized expansion type (G type) in which the cupping expands generally. We evaluated the optic disc in 86 eyes with primary open angle glaucoma (G type 44 eyes L type 42 eyes) to evaluate correlations of age and visual field defects between the 2 groups. Our study revealed that G type patients were significantly younger than those with L type when matched according to visual field defects. We also found that G type was revealed as the nasal step alone but not in L type. These results suggest that in G type, the optic nerve head is diffusely damaged by elevated intraocular pressure and the total nerve fibers are destroyed uniformly. On the other hand, in L type, the vulnerable portion of the optic nerve head is selectively damaged and nerve fibers constituting the optic rim area are destroyed. As a result, L type is likely to form cupping notch and reveal Bjerrum scotoma. These facts correspond to the anatomical structures of nerve fiber layers.