Novel technique of explantation of rigid phakic iris-claw lens and cataract extraction by sutureless manual small-incision surgery

A 38-year-old patient presented to us with complaints of blurred vision and photophobia in the left eye with an uncorrected visual acuity of 20/400, improving to 20/60 with pinhole. The patient underwent phakic iris-claw lens surgery 15 years ago for high myopia. On examination, there was anterior chamber rigid phakic iris-claw lens along with complicated cataract. We planned for sutureless self-sealing 6.5 mm sclerocorneal tunnel for explantation of rigid phakic iris-claw lens along with cataract extraction with irrigating vectis. There was postoperative reduction in astigmatism due to incision planned on steep axis, and visual acuity improved to 20/30 uncorrected. This technique provides significant advantages from the previously described techniques in terms of decreased postop astigmatism, no need for sutures, no issues of chamber instability and iris trauma and without the need for phacoemulsification.

Persistently poor vision in dim illumination after implantation of XtraFocus small-aperture IOL (Morcher)

A 21-year-old patient presents to us with complaints of blurred vision and photophobia in the left eye, with an uncorrected visual acuity of 20/100 improving to 20/30 with pinhole and diagnostic rigid gas permeable lens trial. He had a history of trauma with subsequent cataract extraction, with residual irregular astigmatism and traumatic mydriasis. XtraFocus Pinhole intraocular lens (Morcher) was implanted in the left eye. One week postoperatively, the left eye uncorrected visual acuity improved to 20/30, uncorrected intermediate visual acuity improved to 20/40, and uncorrected near visual acuity improved to J4. The glare and photophobia resolved completely. Surprisingly, the patient complained of severely poor vision in dim illumination. His vision was limited to bare perception of objects and hand movements close to the face. He started facing difficulties in major activities such as driving at night and in dark ambient surroundings such as movie theatres, which persisted to the extent of necessitating explantation of the implant.

Persistent troublesome floaters necessitating the explantation of XtraFocus Pinhole IOL (Morcher)

A 41-year-old patient presented with blurred vision and photophobia in the left eye with an uncorrected visual acuity of 20/150, improving to 20/30 with pinhole and diagnostic rigid gas permeable lens trial. He had a history of trauma with subsequent cataract extraction with residual irregular astigmatism and traumatic mydriasis. XtraFocus Pinhole intraocular lens (Morcher) was implanted in the left eye and the vision improved to 20/40. Postoperatively, the patient experienced significant floaters which persisted to the extent of necessitating explantation of implant.

Xtra focus pinhole IOL (Morchers GMBH) a novel approach to tackle irregular astigmatism and large pupillary defects with a single step surgery

A 69-year-old patient presented to us with traumatic mydriasis with irregular pupil measuring 7 mm, with superior loss of iris tissue and large inferior peripheral iridotomy and pseudophakia. The patient had history of blunt trauma 3 years ago in a fire cracker injury. He was operated elsewhere primarily after the trauma for cataract surgery with intraocular lens implantation and had suboptimal visual outcome with glare and photophobia. He presented to us with irregular pupil and inferior iridectomy with pseudophakia. The uncorrected visual acuity was 20/150 improving to 20/50 with glasses. He had a history of cataract surgery with intraocular lens (IOL) implantation done elsewhere several years back. The patient was not a diabetic or hypertensive. There was a para central corneal scar causing irregular corneal astigmatism. Extra focus pinhole IOL was implanted in sulcus having a pinhole aperture 1.36 mm. Preoperative total corneal higher-order aberrations were 3.3 µ and total corneal coma was 0.97 µ. Postoperatively uncorrected distance visual acuity improved to 20/40 intermediate uncorrected visual acuity improved to 20/30 and uncorrected near visual acuity was J3.

Importance of clinical signs leading to the diagnosis in a case of microbiological smear negative ocular microsporidiosis

A 28-year-old patient presented to us with multifocal coarse raised epithelial lesions in the left eye associated with pain watering redness and blurred vision with a visual acuity of 20/40 in the left eye. The patient had been managed elsewhere with a course of topical moxifloxacin eye-drops four times a day and topical steroids (prednisolone acetate) 1% three times a day for 2 weeks without any resolution, which was stopped 2 days ago prior to presentation at our centre. Gram stain was negative for bacteria as well as microsporidial spores. 10% KOH was negative for fungal hyphae. Based on strong clinical signs of corneal microsporidiosis, in spite of the negative microbiology smear, the patient was started on voriconazole eye-drops five times a day. The lesions started resolving in 5 days and completely healed after 17 days of therapy. No relevant history pertaining to exposure of contaminated water, swimming or history of trauma could be elicited.

Outcome of cataract surgery associated with posterior staphyloma

PURPOSE

To assess the outcome of cataract surgery in eyes with posterior staphyloma and identify predictors of surgical success.

SETTING

Tertiary care referral center.

METHODS

A retrospective analysis was conducted of 107 consecutive patients with posterior staphyloma and 107 control patients who had cataract surgery. Potential associations of preoperative variables with surgical success were analyzed using the chi-square test, multivariate linear regression, and Student t test.

RESULTS

The staphyloma group was younger, had more women, and had a lower mean visual acuity preoperatively than the control group. All patients in the control group and all but 1 in the staphyloma group had intraocular lens (IOL) implantation at the time of cataract extraction. The rates of posterior capsule tear and vitreous loss were similar in the staphyloma and control groups. There was 1 case each of retinal detachment and IOL dislocation in the staphyloma group. The staphyloma group had significantly lower postoperative visual acuity than the control group; however, the percentage in the staphyloma group with a visual acuity of finger counting or worse decreased from 80.4% preoperatively to 16.8% postoperatively and the percentage with an uncorrected visual acuity of 20/160 or better increased from 5.6% to 67.3%. Myopic degeneration was judged to be the cause of postoperative acuity worse than 20/100 in 22.4% in the staphyloma and 0% in the control group; other causes for poor postoperative acuity were similar in the 2 groups. In the staphyloma but not the control group, decreased postoperative acuity was independently associated with age greater than 65 years and axial length greater than 29.0 mm.

CONCLUSIONS

Myopic degeneration may limit the results of cataract extraction in up to one fourth of patients with posterior staphyloma. Nevertheless, a substantial improvement in mean visual acuity resulted that was not associated with a significant increase in surgical complications.

Expulsive iridodialysis: an isolated injury after phacoemulsification

I report a case of blunt trauma to an eye that had had uneventful phacoemulsification through a 5.0 mm self-sealing corneoscleral incision 4 months earlier. Total iris expulsion occurred through the cataract incision without extension of the wound or disruption of the posterior capsule or intraocular lens. A possible mechanism for this injury is discussed and related to the unique properties of the corneoscleral incision.

Topography after repair of full-thickness corneal laceration

PURPOSE

To characterize corneal topography after repair of full-thickness corneal laceration.

SETTING

Ophthalmic emergency room serving as a trauma referral center.

METHODS

Twenty-two eyes with full-thickness corneal lacerations were prospectively studied after standardized surgical repair. Computerized videokeratography was done 2 and 14 weeks after surgery, with the latter measurement corresponding to 6 to 8 weeks after all sutures were removed. Fellow uninjured eyes served as the control group.

RESULTS

Twenty eyes (91%) had a significant reduction in topographic distortion after suture removal. Mean corneal astigmatism, measured by simulated keratometry, was 10.70 diopters (D) +/- 5.90 D (SD) with sutures in place and 2.25 +/- 4.90 D after their removal (P < .005). Eighteen patients (82%) had 2.00 D or less of corneal astigmatism 6 to 8 weeks after all sutures were removed. The final distribution of topographic patterns was bow tie (50%), spherical/oval (36%), and irregular (14%). There was no significant correlation between laceration configuration (curvilinear, jagged, branched wound margins) and final topography. Lacerations that passed within 2.0 mm of the line of sight, however, were significantly more likely to have more than 2.00 D of final astigmatism. Mean central corneal power was 42.40 +/- 3.20 D in the injured eyes and 42.40 +/- 2.40 D in the uninjured fellow eyes.

CONCLUSION

Although high astigmatism is frequently produced by corneal sutures used to repair full-thickness lacerations, the cornea has a substantial topographic memory that results in a marked normalization of contour after suture removal.

Expression of cell cycle-associated proteins in human and rabbit corneal endothelium in situ

PURPOSE

It is unknown why human corneal endothelium exhibits limited capacity to divide while the endothelia of other species, such as rabbit, divide in vivo at wounding and in culture. A potentially valuable source of information concerning why human endothelium has such a limited proliferative capacity lies in elucidating any differences in the molecular events governing the cell cycle of these two species. A recent study of the relative expression of cell cycle-associated proteins in donor corneas suggests that human corneal endothelial cells in vivo have not exited the cell cycle but are arrested in G1-phase. The purpose of the current study was to identify differences in cell cycle protein expression in human and rabbit endothelium that would explain the difference in their relative proliferative capacities. Specifically, the authors first ascertained the relative proliferative status of rabbit corneal endothelial cells in vivo. The expression and intracellular distribution of G1-phase regulatory proteins was then determined in both species, and the results were compared.

METHODS

Corneas from New Zealand white rabbits (weight range, 2 to 3 kg) and from human donors (age range, 6 months to 67 years) were fresh frozen, cryostat sectioned, and prepared for indirect immunofluorescence microscopy using an established protocol. The following monoclonal antibodies were localized in rabbit corneal endothelium only: cyclins D, E, A, and B1; protein kinase p34cdc2; and Ki67, a marker of actively cycling cells. Localization patterns for the following G1-phase regulatory proteins were compared in both human and rabbit corneal endothelia: the tumor suppressors, pRb, p53, and p16INK4, and the transcription factor, E2F. Reverse transcription-polymerase chain reaction studies were conducted to detect mRNA for Ki67 in human and rabbit corneal cells.

RESULTS

Cyclins D, E, and A were localized in the cytoplasm of rabbit corneal endothelium, whereas cyclins B1 and p34cdc2 were detected in the nucleus. No Ki67 protein or mRNA expression was detected in the endothelium of either species. In human and rabbit endothelia, p53 and p16INK4 were localized to the cytoplasm, whereas pRb was detected in the nucleus. E2F exhibited a nuclear and a cytoplasmic localization in each species.

CONCLUSIONS

The corneal endothelium of rabbits stained positively for cyclins D, E, and A and did not stain for Ki67, suggesting that, as in humans, rabbit corneal endothelium in vivo is arrested in G1-phase upstream from Ki67 synthesis. Cyclin E was located in the cytoplasm of rabbit cells, whereas it was found in the nucleus in human endothelium. The apparent difference in cellular distribution of cyclin E in these two species may be significant because this cyclin is active during the G1-/S-phase transition. It is possible that in situ human and rabbit corneal endothelial cells are arrested at different points within G1-phase and/or that the difference in relative proliferative capacity exhibited by the corneal endothelium in these two species may be caused by differences in their relative ability to overcome G1-phase arrest.

Ectopic conjunctivalisation in Stevens-Johnson syndrome

Images

Computerized topography of a full-thickness corneal laceration

A full-thickness corneal laceration was studied by computerized topography. Measurements taken preoperatively and during healing allowed the effects of the injury, its repair, and subsequent suture removal to be isolated and separately analyzed.

Characterization of a phosphodiesterase-immunoreactive polypeptide from rod photoreceptors of developing rd mouse retinas

In the inherited retinal degeneration of rd mice, cyclic GMP accumulates in affected rod photoreceptors prior to their degeneration. A deficiency in the activity of the visual cell phosphodiesterase apparently results in the accumulation of cyclic GMP. The cyclic GMP phosphodiesterase (PDE) of normal mouse photoreceptors is a heteromeric protein complex of about 170 kDa, consisting of the alpha beta catalytic unit and the gamma inhibitory unit. The isolated complex has low enzyme activity but it can be activated by incubation with histone. Affinity-purified polyclonal antibodies against the PDE complex of bovine rod outer segments were prepared and used to identify in retinas of both normal and rd mice PDE-immunoreactive polypeptides which comigrated on SDS-polyacrylamide gels with the large subunits (88 kDa) of the normal PDE complex. During development of normal retinas, the 88 kDa immunoreactive component of the PDE complex were detected by day 7, with immunoreactivity increasing throughout the second postnatal week. In rd retinas, the 88 kDa immunoreactivity increased after 9 postnatal days, decreased during rod photoreceptor degeneration, and was undetectable in mature rd retinas. Under nondenaturing conditions, the PDE-immunoreactive polypeptide of rd retinas sedimented on sucrose gradients with a sedimentation coefficient of 5.6S and an apparent molecular mass of about 105 kDa; no associated histone-activated PDE activity was detected. These findings show that PDE-immunoreactive polypeptides are synthesized in immature rd photoreceptors and that the PDE-immunoreactive polypeptides fail to form a PDE complex which is comparable to that of normal photoreceptors.

Characterization of transducin from bovine retinal rod outer segments. Use of monoclonal antibodies to probe the structure and function of the subunit

A panel of monoclonal antibodies has been developed against the T alpha, T beta and T gamma subunits of bovine transducin. Two anti-T alpha antibodies from this panel (TF15 and TF16) and a third one (4A) against frog T alpha (Witt, P. L., Hamm, H. E., and Bownds, M. D. (1984) J. Gen. Physiol. 84, 251-263) were characterized. Each of these monoclonal antibodies recognizes a different region of T alpha and has a specific effect on the function of transducin. The binding of TF15 is reversibly enhanced by treating T alpha with either 1 M guanidinium chloride or, to a smaller extent, by the removal of bound guanine nucleotide. Its epitope is located in a 12-kDa tryptic fragment containing the binding site for the guanine moiety of GTP. Taken together, these results support previous observations that the conformation of T alpha is modulated by the occupancy of the guanine nucleotide binding site. In contrast to TF15, TF16 recognizes only the native form of T alpha. Its epitope resides within the central portion of the T alpha molecule. While T alpha-bound TF16 does not inhibit either pertussis toxin-catalyzed ADP-ribosylation, rhodopsin binding, or transducin subunit interaction, it blocks both the light-activated uptake of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and the GTP-dependent elution of transducin from photolyzed rhodopsin. These effects are unlikely to be caused by the occupation of the guanine nucleotide binding site by TF16 because this antibody quantitatively precipitates T alpha-GTP gamma S. We propose that bound TF16 locks T alpha in a conformation that prevents the entrance of guanine nucleotide and favors T beta gamma association. In contrast to TF16, the epitope of 4A was mapped to the amino-terminal region of T alpha. This monoclonal antibody blocks pertussis toxin-catalyzed ADP-ribosylation, GTP gamma S uptake, and T alpha-T beta gamma association. Moreover, the binding site for 4A becomes inaccessible when transducin binds to photolyzed rhodopsin. These results suggest that the inhibitory effects of 4A are due to a simultaneous steric blockage of both the interaction of T alpha with T beta gamma and their binding to photolyzed rhodopsin. The results obtained from these studies are correlated with the structure and function of T alpha.

Characterization of transducin from bovine retinal rod outer segments. Participation of the amino-terminal region of T alpha in subunit interaction

The GTP-induced dissociation of T alpha from T beta gamma initiates the release of transducin from photolyzed rhodopsin and the subsequent activation of the cGMP phosphodiesterase. In this study, site-specific proteolysis and immunoprecipitation were used to map the domain of T alpha that interacts with T beta gamma. We found that Staphylococcus aureus V8 protease rapidly removes a small fragment from T alpha under native conditions, resulting in the formation of a single 38-kDa polypeptide (T alpha'). Under the same conditions, T beta gamma remains intact. A 4.5-fold decrease in the rate of T alpha cleavage by S. aureus protease was observed in the presence of T beta gamma, suggesting T beta gamma binding blocks the protease-sensitive site on T alpha. Amino acid sequence analysis indicated that T alpha' is derived from the cleavage of T alpha at Glu-21. The ability of T alpha' to interact with and activate the retinal phosphodiesterase is not diminished. However, T alpha' is unable to participate in T beta gamma-dependent activities such as the light-stimulated binding of guanine nucleotides, binding to photoexcited rhodopsin, and ADP-ribosylation catalyzed by pertussis toxin. Moreover, the anti-T alpha monoclonal antibody TF16 was able to precipitate T beta gamma in the presence of T alpha, but not with either T alpha' or T alpha-guanosine 5'-O-(3-thiotriphosphate). We conclude that the amino-terminal region of T alpha participates in T beta gamma interaction and discuss our results with respect to the known structure and function of transducin.

Infection of neuroretinal cells in vitro by avian sarcoma viruses UR1 and UR2: transformation, cell growth stimulation, and changes in transducin levels

Infection in vitro of differentiating chick embryo neuroretinal cells with avian sarcoma viruses UR1 and UR2 results in mitogenic stimulation and morphologic conversion of both support neuronal cells. This was shown by the continuous propagation of transformed cells for over 4 months and growth of reaggregated colonies in liquid medium as well as in soft agar. Production of the transforming proteins p 150 gag-fps and p68 gag-ros of UR1 and UR2, respectively, was similar to that of transformed chick embryo fibroblasts, as judged from in vitro kinase activity assays. The two protein subunits, T beta and T gamma, but not T alpha of the GTP binding protein transducin, found in the retina of many animal species, were present in control neuroretinal cells. Infection with Rous sarcoma virus or UR2 resulted in an inhibition of T gamma synthesis and enhancement of T beta-like protein production.

Immunological determination of transducin content in retinas exhibiting inherited degeneration

The inherited disorders of rd mice and affected Irish setter dogs are characterized by the accumulation of cyclic GMP (cGMP). Since the cGMP level in normal retinal rods is regulated by a light-activated enzyme cascade involving rhodopsin, transducin, and phosphodiesterase, an abnormality associated with any of these three proteins would cause cGMP accumulation. In order to determine the relationship between different forms of retinal degeneration and the transducin content in the affected retinas, affinity-purified antibodies directed against the individual subunits of bovine transducin were prepared. These antibodies, which recognized transducin in many vertebrate species, were used to compare the retinal content of this protein at various stages of inherited photoreceptor degeneration. In each of the disorders studied (rd and rds mice, RCS rat, and affected Irish setter dog), retinas at early stages of degeneration displayed two characteristics similar to those of normal control retinas. First, all three subunits of transducin were detected and found to have normal electrophoretic mobility, suggesting that these disorders are unlikely to be due to changes in the composition of transducin subunits. Second, the amount of cross-reactive T beta always exceeded those of T alpha and T gamma. This disproportionately higher amount of T beta-like protein became more pronounced as the visual cells degenerated. In retinas which had undergone complete photoreceptor degeneration, cross-reactive T alpha and T gamma were undetectable. In contrast, anti-T beta gamma antibodies detected an amount of T beta-like polypeptide corresponding to 10-25% of the control. Since our anti-T beta gamma antibodies recognize the beta subunit of the GTP-binding N proteins of the adenylate cyclase system, this finding suggests that this residual T beta-like protein, which is not part of transducin, may be associated with other GTP-binding regulatory proteins.

Characterization of transducin from bovine retinal rod outer segments. Mechanism and effects of cholera toxin-catalyzed ADP-ribosylation

Transducin, a guanine nucleotide-binding protein consisting of two subunits (T alpha and T beta gamma), mediates the signal coupling between rhodopsin and a membrane-bound cyclic GMP phosphodiesterase in retinal rod outer segments. The T alpha subunit is an activator of the phosphodiesterase, and the function of the T beta gamma subunit is to physically link T alpha with photolyzed rhodopsin. In this study, the mechanism of cholera toxin-catalyzed ADP-ribosylation of T alpha has been examined in a reconstituted system consisting of purified transducin and stripped rod outer segment membranes. Limited proteolysis of the labeled T alpha with trypsin indicated that the inserted ADP-ribose is located exclusively on a single proteolytic fragment with an apparent molecular weight of 23,000. Maximal incorporation of ADP-ribose was achieved when guanosine 5'-(beta, gamma-imido)triphosphate (Gpp(NH)p) and T beta gamma were present at concentrations equal to that of T alpha and when rhodopsin was continuously irradiated with visible light in the 400-500 nm region. The stimulating effect of illumination was related to the direct interaction of the retinal chromophore with opsin. These findings strongly suggest that a transient protein complex consisting of T alpha X Gpp(NH)p, T beta gamma, and a photointermediate of rhodopsin is the required substrate for cholera toxin. Single turnover kinetic measurements demonstrated that the ADP-ribosylation of T alpha coincided with the appearance of a population of transducin molecules having a very slow rate of GTP hydrolysis. The hydrolysis rate of the bound GTP for this population was 1.1 X 10(-3)/s, which was 22-fold slower than the rate for the unmodified transducin.