Congenital abnormalities of the retinal vasculature in neurofibromatosis type I

Ocular blood vessel arrangement in choroidal coloboma

OBJECTIVE

To describe the ocular blood vessel arrangement in choroidal coloboma eyes.

METHODS

In this retrospective, observational cross-sectional study, fundus images from 69 coloboma eyes of 45 patients were classified as per Ida Mann's classification. The arrangement and distribution of retinal, choroidal, and episcleral vessels, as well as vortex veins, were observed in non-colobomatous, colobomatous, and extra-colobomatous regions.

RESULTS

Seventy-eight colobomas were identified. There were 12 type 1, 13 type 2, 10 type 3, 13 type 4, 11 type 5, 4 type 6 and 15 type 7 colobomas respectively. In most cases of type 1 and 2 colobomas, origin of retinal blood vessels could not be determined. In colobomas type 3-7, retinal blood vessels originated either from the optic disc centre or, rarely, from the optic disc or coloboma margin. Eyes with large and deep type 1, 2, 3 and 7 colobomas showed prominent choroidal vessels in the non-colobomatous region and around the coloboma. Small choroidal colobomas lacked prominent choroidal vessels. Similarly, prominent extraocular episcleral vessels within the coloboma bed were observed in eyes with colobomas of types 1, 2, 3 and 7. Vortex veins were visible in 70% of coloboma eyes. They were more commonly seen with small focal colobomas and less frequently with large deep colobomas.

CONCLUSION

Coloboma eyes have variations in the arrangement and distribution of ocular blood vessels. The position, size, and antero-posterior extent of the choroidal coloboma are the primary determinants of how these blood vessels are arranged. Future research would benefit from additional imaging with indocyanine green angiography.

Insights into Novel Choroidal and Retinal Clinical Signs in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is a rare inherited neurocutaneous disorder with a major impact on the skin, nervous system and eyes. The ocular diagnostic hallmarks of this disease include iris Lisch nodules, ocular and eyelid neurofibromas, eyelid café-au-lait spots and optic pathway gliomas (OPGs). In the last years, new manifestations have been identified in the ocular district in NF1 including choroidal abnormalities (CAs), hyperpigmented spots (HSs) and retinal vascular abnormalities (RVAs). Recent advances in multi-modality imaging in ophthalmology have allowed for the improved characterization of these clinical signs. Accordingly, CAs, easily detectable as bright patchy nodules on near-infrared imaging, have recently been added to the revised diagnostic criteria for NF1 due to their high specificity and sensitivity. Furthermore, subclinical alterations of the visual pathways, regardless of the presence of OPGs, have been recently described in NF1, with a primary role of neurofibromin in the myelination process. In this paper, we reviewed the latest progress in the understanding of choroidal and retinal abnormalities in NF1 patients. The clinical significance of the recently revised diagnostic criteria for NF1 is discussed along with new updates in molecular diagnosis. New insights into NF1-related neuro-ophthalmic manifestations are also provided based on electrophysiological and optical coherence tomography (OCT) studies.

Prospects for the use of statins in the treatment of neurofibromatosis type 1

Neurofibromatosis type 1 is caused by a germline mutation in the NF1 gene encoding the tumor suppressor neurofibromin. Deficiency of this protein causes hyperactivation of Ras proto-oncogenes. This leads to the development of tumors. Ras proteins undergo prenylation, which is inhibited by inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme-A reductase. Therefore, statins can be proposed as anticancer drugs in the complex treatment of neurofibromatosis type 1. Clinical studies have proven the effectiveness of statins in the treatment of sporadic malignant neoplasms, in the pathogenesis of which mutations in the NF1 gene play an important role. Various pathways of the influence of these drugs on the development of tumors are described, including the activation of autophagy, ferroptosis, suppression of proliferation, stimulation of antitumor immunity, and effects on the microenvironment of neoplasms. Data on the effect of statins on the development and progression of neurofibromas in patients with neurofibromatosis type 1 are not presented in the scientific literature. However, it was found that statins enhance the effect of anticancer drugs, the use of which in monotherapy against malignant neoplasms associated with neurofibromatosis is ineffective. In this regard, despite the inefficiency of statins in cognitive disorders in patients with neurofibromatosis type 1, the introduction of these drugs into clinical practice in combination with other drugs could provide a pleiotropic effect, affect various links in the pathogenesis of the disease.