Analyzing pre-symptomatic tissue to gain insights into the molecular and mechanistic origins of late-onset degenerative trinucleotide repeat disease

How genetic defects trigger the molecular changes that cause late-onset disease is important for understanding disease progression and therapeutic development. Fuchs' endothelial corneal dystrophy (FECD) is an RNA-mediated disease caused by a trinucleotide CTG expansion in an intron within the TCF4 gene. The mutant intronic CUG RNA is present at one-two copies per cell, posing a challenge to understand how a rare RNA can cause disease. Late-onset FECD is a uniquely advantageous model for studying how RNA triggers disease because: (i) Affected tissue is routinely removed during surgery; (ii) The expanded CTG mutation is one of the most prevalent disease-causing mutations, making it possible to obtain pre-symptomatic tissue from eye bank donors to probe how gene expression changes precede disease; and (iii) The affected tissue is a homogeneous single cell monolayer, facilitating accurate transcriptome analysis. Here, we use RNA sequencing (RNAseq) to compare tissue from individuals who are pre-symptomatic (Pre_S) to tissue from patients with late stage FECD (FECD_REP). The abundance of mutant repeat intronic RNA in Pre_S and FECD_REP tissue is elevated due to increased half-life in a corneal cells. In Pre_S tissue, changes in splicing and extracellular matrix gene expression foreshadow the changes observed in advanced disease and predict the activation of the fibrosis pathway and immune system seen in late-stage patients. The absolute magnitude of splicing changes is similar in pre-symptomatic and late stage tissue. Our data identify gene candidates for early drivers of disease and biomarkers that may represent diagnostic and therapeutic targets for FECD. We conclude that changes in alternative splicing and gene expression are observable decades prior to the diagnosis of late-onset trinucleotide repeat disease.

Early onset endophthalmitis caused by Aspergillus species following cataract surgery

PURPOSE

To report a series of patients with early onset Aspergillus endophthalmitis following cataract surgery.

DESIGN

Retrospective consecutive case series.

METHODS

Medical records were reviewed of all cases of endophthalmitis caused by Aspergillus after cataract surgery treated at the authors' practices between 1992 and 2005.

RESULTS

Five patients were identified. Two patients were immunocompromised (one on oral corticosteroids and one on chemotherapy for lung cancer). The mean number of days between cataract surgery and diagnosis with endophthalmitis was 29 (range, 10 to 62 days). Three eyes (60%) were enucleated despite a variety of treatments. In addition to vitrectomy and injection of antifungal agents, the other two eyes underwent surgical debridement of a localized necrotic nidus. Final visual acuity was 20/30 in one eye and 20/200 in the remaining eye.

CONCLUSIONS

Aspergillus should be considered in the differential diagnosis of early onset endophthalmitis following cataract surgery. Visual outcomes are generally poor and enucleation is common in these patients.

Refractive keratotomy in keratoconus suspects

BACKGROUND

We utilized videokeratography to determine the frequency of keratoconus suspects in a refractive surgery population, and compared the results of refractive keratotomy in these patients to those of patients with normal corneal topography.

METHODS

The records of 67 consecutive patients (120 eyes) undergoing refractive keratotomy were reviewed retrospectively. Quantitative measurements of relative inferior corneal steepening (inferior-superior value, I-S value) were obtained from preoperative videokeratography.

RESULTS

Three of 120 eyes (3 of 67 patients, 4.5%) were identified as keratoconus suspects based on I-S (inferior-superior) values greater than +1.74 (range, +1.76 to +2.00), which represented two standard deviations (+/- 0.66) above the mean (+0.42). All three of these eyes achieved postoperative uncorrected visual acuity of 20/30 or better. Of those eyes with normal preoperative topography (I-S value +1.74 or less), 90 of 112 (80%) achieved postoperative uncorrected visual acuity of 20/30 or better, and 105 of 112 (94%) achieved 20/40 or better.

CONCLUSIONS

Although long-term follow up is needed to confirm stability of refractive surgery outcome, it appears that keratoconus suspects can obtain acceptable results with refractive keratotomy. Studies on larger patient populations using videokeratography are needed to better define keratoconus, keratoconus suspects, and normal variants of corneal topography and to determine how eyes with abnormal topography respond to refractive keratotomy.

Primary intraocular lens implantation in the setting of penetrating ocular trauma

PURPOSE

To evaluate the clinical outcome of patients who underwent lensectomy and intraocular lens (IOL) implantation at the time of primary repair of a penetrating ocular injury.

METHODS

A review of 14 patients who sustained cataracts and lens rupture in the setting of a corneal laceration to determine anatomic and visual outcome, in addition to complications related to the primary IOL.

RESULTS

The IOL remained anatomically stable in all 14 patients with no complications encountered at implantation or after surgery. Final visual acuity in 9 of the 14 patients was 20/40 or better. Six patients underwent pars plana vitrectomy for removal of an intraocular foreign body.

CONCLUSION

Intraocular lens implantation at the time of lensectomy and primary repair of a corneal laceration allows good visual rehabilitation with restoration of binocular function and serves as an alternative to contact lens correction in select patients.

Cutaneous malignant melanoma with diffuse intraocular metastases

A 63-year-old man with a history of cutaneous melanoma and a 3-month history of visual loss in his right eye presented with marked pigmentation of the anterior-segment structures, including trabecular meshwork, iris, and lens surface, with pigment dispersion in the aqueous and anterior vitreous in the right eye. Clinical examination and echography showed no evidence of an intraocular tumor although metastatic melanoma was suspected. Pathologic examination revealed numerous heavily pigmented melanoma cells throughout the anterior segment of the eye, mainly concentrated in the anterior vitreous near the ciliary body. No discrete tumor was found on multiple sections through the globe.

Oral therapy in diffuse unilateral subacute neuroretinitis

Diffuse unilateral subacute neuroretinitis is an endemic disease associated with severe visual loss in the southeastern and midwestern United States and the Caribbean. It is caused by a single nematode that may wander in the subretinal space for many months or years. Until recently, the only effective treatment has involved the difficult and time-consuming biomicroscopic detection of the worm followed by photocoagulation. This report describes the use of oral thiabendazole in four patients with presumed diffuse, unilateral, subacute neuroretinitis. Serial fundus photography was used to detect evidence of early destruction of the worm.

Noninvasive repositioning of a posterior chamber intraocular lens following pupillary capture

A case of pupillary capture of a posterior chamber intraocular lens (IOL) is presented. A nonsurgical approach that may help reposition an IOL optic entrapped in a pupillary capture when chemical mydriasis fails is described. Suggestions for a logical progression of nonsurgical procedures to help release optic capture are presented. Possible causes and preventative measures to decrease the incidence of pupillary capture of a posterior chamber IOL are discussed.

Successful oral therapy for diffuse unilateral subacute neuroretinitis

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Primary chiasmal germinoma. A case report and review of the literature

A case is presented in which an adult man with painless progressive loss of vision subsequently was found to have a primary suprasellar/perichiasmal germinoma (ectopic pinealoma). A review of the literature revealed 93 similar cases of germinoma occurring in the perichiasmal region and these are tabulated. The diagnosis and management of this lesion are discussed, including the recognition of the characteristic neuroendocrinologic triad of diabetes insipidus, visual changes, and hypopituitarism. Of 64 cases from the literature wherein presenting symptoms were reported, 56 (87.5%) had diabetes insipidus, 53 (82.8%) visual changes, and 36 (56%) hypopituitarism. A review of the literature suggests that diabetes insipidus is usually the initial symptom in suprasellar germinoma. However, we wish to emphasize the ophthalmologic presentation of this entity, because of ophthalmologic presentation of this entity, because patients in the age group most affected (adolescents) will often not recognize symptoms of diabetes insipidus, but will first seek medical attention for painless progressive loss of vision suggestive of chiasmal compression. The radiosensitivity of this lesion is also discussed. Of 61 patients receiving irradiation therapy, 42 (68%) were surviving at the time of their individual case report. No patient in the review survived without irradiation therapy.