Lisch Epithelial Corneal Dystrophy Is Caused by Heterozygous Loss-of-Function Variants in MCOLN1

PURPOSE

To report the genetic etiology of Lisch epithelial corneal dystrophy (LECD).

DESIGN

Multicenter cohort study.

METHODS

A discovery cohort of 27 individuals with LECD from 17 families, including 7 affected members from the original LECD family, 6 patients from 2 new families and 14 simplex cases, was recruited. A cohort of 6 individuals carrying a pathogenic MCOLN1 (mucolipin 1) variant was reviewed for signs of LECD. Next-generation sequencing or targeted Sanger sequencing were used in all patients to identify pathogenic or likely pathogenic variants and penetrance of variants.

RESULTS

Nine rare heterozygous MCOLN1 variants were identified in 23 of 27 affected individuals from 13 families. The truncating nature of 7 variants and functional testing of 1 missense variant indicated that they result in MCOLN1 haploinsufficiency. Importantly, in the homozygous and compound-heterozygous state, 4 of 9 LECD-associated variants cause the rare lysosomal storage disorder mucolipidosis IV (MLIV). Autosomal recessive MLIV is a systemic disease and comprises neurodegeneration as well as corneal opacity of infantile-onset with epithelial autofluorescent lysosomal inclusions. However, the 6 parents of 3 patients with MLIV confirmed to carry pathogenic MCOLN1 variants did not have the LECD phenotype, suggesting MCOLN1 haploinsufficiency may be associated with reduced penetrance and variable expressivity.

CONCLUSIONS

MCOLN1 haploinsufficiency is the major cause of LECD. Based on the overlapping clinical features of corneal epithelial cells with autofluorescent inclusions reported in both LECD and MLIV, it is concluded that some carriers of MCOLN1 haploinsufficiency-causing variants present with LECD.

The Hematologic Definition of Monoclonal Gammopathy of Undetermined Significance in Relation to Paraproteinemic Keratopathy (An American Ophthalmological Society Thesis)

PURPOSE

To determine if paraproteinemic keratopathy (PPK) in the setting of monoclonal gammopathy of undetermined significance (MGUS) causes distinct patterns of corneal opacification that can be distinguished from hereditary, immunologic, or inflammatory causes.

METHODS

A retrospective, interventional study of patients showed distinct bilateral opacity patterns of the cornea at the eye clinics of Hanau, Mainz, Helsinki, Marburg, and Berlin between 1993 and 2015. Data on patient characteristics and clinical features on ophthalmic examination were collected, and serum protein profiles were evaluated. A literature review and analysis of all published studies of MGUS with PPK is also presented.

RESULTS

The largest group of patients diagnosed with MGUS-induced PPK is analyzed in this study. We studied 22 eyes of 11 patients (6 male, aged 43 to 65, mean age 54; 5 female, aged 49 to 76, mean age 61) with distinct corneal opacities and visual impairment who were first suspected of having hereditary, inflammatory, or immunologic corneal entities. Subsequently, serum protein electrophoresis revealed MGUS to be the cause of the PPK. Literature review revealed 72 patients with bilateral PPK (34 male, mean age 57; 38 female, mean age 58) in 51 studies of MGUS published from 1934 to 2015 and disclosed six additional corneal opacity patterns.

CONCLUSIONS

This thesis shows that MGUS is not always an asymptomatic disorder, in contrast to the hematologic definition, which has no hint of PPK. The MGUS-induced PPK can mimic many other diseases of the anterior layer of the eye. A new clinical classification for PPK in MGUS is proposed.

Erratum: The Hematologic Definition of Monoclonal Gammopathy of Undetermined Significance in Relation to Paraproteinemic Keratopathy (An American Ophthalmological Society Thesis)

[This corrects the article on p. T7 in vol. 114, PMID: 28050052.].

[Revision procedures after canaloplasty]

Canaloplasty is a recently introduced non-penetrating surgical technique for glaucoma, which seeks to improve the natural outflow of aqueous humor through Schlemm's canal and the collector channels. Just as in all forms of glaucoma surgery there are a certain number of failures of the procedure and further surgery is often needed to reduce the intraocular pressure in these cases. This article describes some of the revision procedures after canaloplasty.

Conjunctival amyloidosis -- clinical and histopathologic features

PURPOSE

Conjunctival amyloidosis is a rare disorder. It is often clinically not suspected or diagnosed. This study intended to demonstrate the clinical and histopathologic features of this infrequent disease, including an immunohistochemical search for amyloidotic proteins.

METHODS

Retrospective case series of the clinical and histopathologic characteristics of six patients with conjunctival amyloidosis. Immunohistochemical analysis with respect to possible amyloidotic components of the conjunctival deposits was performed.

RESULTS

The diagnosis of amyloidosis was not suspected in all six cases presenting with an amelanotic conjunctival lesion. In three patients a conjunctival tumor of unknown origin, in one case each a papillomatous alteration of the conjunctiva, a conjunctival granulomatous inflammation, and a lymphoma were assumed respectively. The diagnosis of amyloidosis was made by histopathology. Immunohistochemical examination found lambda and kappa light chains as well as prealbumin within the amyloid deposits in one of the six specimens.

CONCLUSIONS

The diagnosis of amyloidosis has to be kept in mind in cases with an unclear conjunctival mass or inflammatory process. Only a tissue biopsy is able to prove the diagnosis. A possible underlying systemic disease has to be ruled out.

[Discrete bilateral corneal deposits in a young woman]

A 17-year-old asymptomatic girl presented with discrete bilateral deposits in the superficial corneal stroma. The diagnosis of very early and in this form as yet undescribed manifestation of Schnyder's corneal dystrophy, was only possible based on the family history.

[Ophthalmologists in the proximity of Adolf Hitler]

Adolf Hitler met or at least knew about 5 ophthalmologists. The chair of ophthalmology in Berlin, Walther Löhlein, personally examined Hitler's eyes at least two times. The chair of ophthalmology in Breslau, Walter Dieter, developed "air raid protection spectacles" with the aid of high representatives of the NS-system and probably Adolf Hitler himself. Heinrich Wilhelm Kranz became rector of the universities of Giessen and Frankfurt/Main. He was known as a very strict advocate of the NS-race hygiene. Werner Zabel made plans for Hitler's diet and tried to interfere with Hitler's medical treatment. Finally, Hellmuth Unger was an influential representative of the medical press and a famous writer. Three of his novels with medical topics were made into a film which Hitler probably saw. Hitler had, so to say, a small "ophthalmological proximity" which, however, did not play a significant role for himself or the NS-state.

[m4 muscarinic receptors of the cornea : muscarinic cholinoceptor-stimulated inhibition of the cAMP-PKA pathway in corneal epithelial and endothelial cells]

BACKGROUND

Muscarinic cholinoceptors have been found in all types of ocular tissue, e.g. in corneal epithelium and endothelium. Latest research has focused only on the m5 cholinoceptor subtype. However, previous studies have also indicated the presence of m2 or m4 receptor subtypes in corneal tissue. The aim of this study was to show the decrease of intracellular cAMP formation and protein kinase A (PKA) activity after stimulation of m2 or m4 cholinoceptors in bovine corneal epithelial and endothelial cells. MATERIALS UND METHODS: Muscarinic cholinoceptors were studied using polyclonal antibodies. The cAMP concentration was determined with an enzyme immunoassay and PKA activity was estimated by the consumption of ATP.

RESULTS

Immunocytochemistry, immunofluorescence and immunoblotting revealed the presence of the m4 muscarinic cholinoceptor subtype but not of the m2 receptor subtype in bovine corneal epithelial and endothelial cells. In bovine corneal epithelium and endothelium protein cAMP formation was decreased and PKA activity was inhibited by acetylcholine in a dose-dependent manner (p<0.001).

CONCLUSION

The findings indicate that stimulation of m4 muscarinic cholinoceptors inhibits the cAMP-PKA pathway in corneal epithelial and endothelial cells resulting in decreased protein kinase A activity. Further work will be needed to clarify the physiological role of this signaling pathway in corneal epithelium and endothelium.

Cyclo-oxygenase-2 expression in photon-radiated and non-radiated uveal melanomas

PURPOSE

To determine and compare cyclo-oxygenase-2 (COX-2) expression in photon-radiated and non-radiated malignant uveal melanomas and to analyse the correlation between COX-2 expression and prognosis.

METHODS

Immunohistochemical staining for COX-2 was performed on 21 uveal melanomas that were endoresected after prior stereotactic radiotherapy with photons and on 22 tumours that were treated by endoresection without prior radiotherapy. COX-2 staining was further analysed in respect to cell type, maximal prominence, time interval between radiotherapy and surgery, apoptotic index (AI), proliferative index (PI) and the development of metastatic disease.

RESULTS

There was no difference in COX-2 expression between radiated and non-radiated melanomas (P>0.15). COX-2 staining correlated with neither the tumour prominence (P>0.40) nor the AI or the PI (both P>0.35). Tumours with high COX-2 expression were significantly more likely to develop metastasis (P=0.022).

CONCLUSION

Radiotherapy with photons does not induce COX-2 expression in malignant melanomas of the uvea. But high COX-2 expression may be a marker for poor prognosis.

[Glaucoma drainage implants]

INTRODUCTION

The number of available glaucoma drainage implants has increased in recent years and now offers additional therapeutic opportunities in refractory glaucoma patients.

METHODS

In drainage surgery two different functional principles are practised. The most commonly used implants (Ahmed, Krupin, Schocket, Molteno, Baerveldt) drain ocular fluid via a silicone tube into an episcleral reservoir. Multiple studies have compared the operative results of tubes, which differ in insertion, valve, material and surface characterstics. In analogy a miniature stainless steel implant (Ex-PRESS) is implanted at the limbus into the anterior chamber and drains subconjunctivally. These implants shunt ocular fluid under a scleral flap or directly under the conjunctiva. Intrascleral systems (Seton, SLOX, Silicone tubes) drain ocular fluid from the anterior chamber into the suprachoroidal space to regulate intraocular pressure (IOP).

RESULTS

In the literature the postoperative success rates in tube shunts range between 22 % and 100 % depending on glaucoma form and implant. Most of the studies were retrospective. Miniature stainless steel devices (Ex-PRESS) placed directly under the conjunctiva may cause erosion of the conjunctiva and hypotony. Implantation under a scleral flap decreases these complications. Compared with trabeculectomy the implantation of this shunt under a scleral flap reduces the early postoperative rate of hypotony and choroidal effusion. Microimplants of Schlemm's canal ab externo or interno should reduce the intraocular pressure by connecting the anterior chamber and Schlemm's canal. Suprachoroidal shunts are an option in patients with scarred conjunctiva. Though, complications of fibrous encapsulation and dislocation are described.

DISCUSSION

The development of drainage implants allows the reduction or avoidance of complications which are typical of traditional glaucoma filtering surgery. However, in the absence of long-term follow-ups, the procedures with their new side effects have to be further evaluated.

[The situation of ophthalmic pathology in Germany: the current status]

BACKGROUND

Ophthalmic pathology with its 150 year-old tradition is a subspecialty which since its beginning has contributed substantially to progress in ophthalmology. Nevertheless, deactivation or even termination of ophthalmopathological laboratories has occurred in the past years mainly due to economic pressure. In order to evaluate the situation and future perspectives of the existing, active laboratories in Germany and to ask for the kind of support desired from the Section for Ophthalmic Pathology of the German Ophthalmological Society (DOG) a survey was carried out using a questionnaire.

RESULTS

The main results were as follows. 1. Specialised ophthalmic pathology is performed in Germany almost exclusively in laboratories integrated in university eye clinics. 2. There is close cooperation with institutes for pathology and dermatopathology. 3. The main focus is placed on the cornea, tumours of the eye and its adnexae, and the conjunctiva. 4. The number of ophthalmopathological specimens investigated per year is generally below 1000 and often below 500. 5. The diagnostic spectrum and equipment of the laboratories is generally good. 6. There are some deficits concerning ophthalmopathological education and the status of ophthalmic pathology within the clinics. 7. A considerable number of scientific publications is generated by the members of the laboratories. 8. At present there is only minimal fear that the own laboratory will be eliminated in the near future. 9. Ophthalmic pathology is established as an integral component of ophthalmology in patient care and, even more, in ophthalmic research. 10. The DOG-Section "Ophthalmic pathology" is requested to initiate stays in foreign laboratories, to initiate scientific multicentre studies, and to support activities dedicated to preserve the ophthalmopathological laboratories.

DISCUSSION

For the first time valid data concerning the situation of ophthalmopathological laboratories in Germany have been collected. The information gathered can and should be used as an argument for the preservation and, if possible, even expansion of the occupation with normal and pathologic eye morphology at eye hospitals in and beyond Germany.

Rapid development of band keratopathy of corneal graft associated with treatment with intracameral recombinant tissue plasminogen activator for postoperative fibrin reaction

PURPOSE

To report a corneal transplant complication associated with intracameral recombinant tissue plasminogen activator (rTPA) treatment of postoperative fibrin reaction.

METHODS

In a 71-year-old patient, a triple procedure was performed for perforated rheumatic ulcer and secondary cataract.

RESULTS

A dense band keratopathy developed rapidly within 36 hours after the use of intracameral injection of rTPA for the treatment of a dense fibrin clot.

CONCLUSIONS

This is the first report of rapid development of massive band keratopathy in a corneal graft after triple procedure and treatment with intracameral rTPA. Intracameral rTPA should be used with caution in patients with attenuated endothelium.

Primary silicone oil tamponade in the management of severe intraocular foreign body injuries: an 8-year follow-up

PURPOSE

To evaluate the long-term outcome of pars plana vitrectomy and primary silicone oil tamponade in patients with severe intraocular foreign body (IOFB) injuries and high risk of proliferative vitreoretinopathy (PVR).

METHODS

This retrospective consecutive study included 23 patients with severe IOFB injuries who had extensive lacerations including sclera, choroid, and retina, and were complicated by predictive factors for elevated proliferative activity and an unfavorable outcome. All patients underwent pars plana vitrectomy, removal of the IOFB, and primary silicone oil tamponade and were followed up for a mean 8.9 years. Main functional outcome was assessed as final best-corrected visual acuity. Anatomic success was defined as permanent retinal attachment.

RESULTS

PVR occurred in 70% of all eyes and required 16 revisions. Silicone oil was removed in 78% of the eyes after a mean tamponade duration of 9.1 months. Complete retinal attachment was achieved in 83% of the eyes. Three eyes developed a persisting hypotony that was stabilized under permanent silicone oil. Functional stabilization was observed in the third year resulting in a final visual acuity of 20/630. Useful vision of better than 20/400 could be preserved in 55% of the patients. Only one eye underwent a late enucleation after 6.8 years.

CONCLUSIONS

Primary silicone oil stabilizes the retina during the critical period of active PVR and may limit the visual loss in selected high-risk eyes in the long term.

[Resistance of limbo-keratoplasty to blunt trauma]

BACKGROUND

Traumatic wound dehiscence is a rare complication after penetrating keratoplasty. Limbo-keratoplasty seems to alter the pattern of rupture after blunt trauma.

CASE REPORT

We report on one patient with dehiscence of a penetrating limbo-keratoplasty after blunt trauma.

RESULTS

The dehiscence occurred over the entire extent of the clear corneal scar, whereas the sclero-corneal interface remained adapted.

CONCLUSIONS

This case suggests a different tensile strength of these two scar types, possibly associated with their different grades of vascularization or epithelialization.

[Effect of timolol on central corneal thickness and endothelial cell density]

BACKGROUND

The measurement of corneal thickness plays an increasing role in glaucoma screening and diagnosis. The influence of a variety of drugs on corneal thickness is well established. Especially for antiglaucomateous drugs this effect seems to be important. However, little is known about the influence of beta receptor antagonists on corneal thickness. The aim of this study was to provide evidence of the effect of timolol on central corneal thickness and endothelial cell density.

MATERIALS AND METHODS

Ten healthy volunteers (five women and five men) with a mean age of 29 years (range 25 to 56 years) were examined in a double-blind, prospective and randomised pilot study. Intraocular pressure, corneal thickness and endothelial cell density was estimated before as well as fifteen minutes, 24, 48, 72 and 96 hours after application of timolol 0.5 % eye drops twice daily. The partner eye received sodium hyaluronate eye drops twice daily and served as a control.

RESULTS

The application of timolol showed a decrease of intraocular pressure from initially 12 mmHg to 9 mmHg after four days (p = 0,0188) as well as an increase of corneal thickness from 537 microm to 557 microm after four days (p = 0,0659). There was no change of intraocular pressure (p = 0,9935) or corneal thickness (p = 0,9998) in the control eyes. There was also no effect of timolol (p = 0,2782) or sodium hyaluronate (p = 0,1940) on endothelial cell density.

CONCLUSIONS

The study provides evidence of the influence of beta receptor antagonists on corneal thickness. This effect may be caused by receptor mediated influences on corneal ion and fluid transport. Further studies are needed to show if the increase of corneal thickness after application of topical timolol has clinical importance.

[Protein kinase C isoforms in corneal epithelium and endothelium]

BACKGROUND

Protein kinase C (PKC) plays a key role in cell metabolism. Three subgroups and 12 isoforms have been isolated so far, catalysing specific functions in cell metabolism. The demonstration of PKC subtypes in corneal tissue has been inconsistent. The aim of this study was to verify the expression of several PKC subgroups and isoforms in human and bovine corneal epithelial and endothelial cells.

MATERIALS AND METHODS

PKC subgroups and isoforms were studied using polyclonal antibodies.

RESULTS

Antibodies to PKC-alpha, -delta, -epsilon and -zeta, representing all three PKC subgroups, bound in human and bovine corneal epithelium and endothelium. No binding was found for antibodies to PKC-beta2.

CONCLUSIONS

For the first time the presence of all three PKC subgroups was demonstrated in human and bovine corneal epithelial and endothelial cells. Further studies are needed to show the role of these subgroups in cellular functions such as cell proliferation and differentiation.