[Update on endocrine orbitopathy]

3-D cephalometry of the the orbit regarding endocrine orbitopathy, exophthalmos, and sex

Purpose

This study aimed at evaluating the orbital anatomy of patients concerning the relevance of orbital anatomy in the etiology of EO (endocrine orbitopathy) and exophthalmos utilizing a novel approach regarding three-dimensional measurements. Furthermore, sexual dimorphism in orbital anatomy was analyzed.

Methods

Orbital anatomy of 123 Caucasian patients (52 with EO, 71 without EO) was examined using computed tomographic data and FAT software for 3-D cephalometry. Using 56 anatomical landmarks, 20 angles and 155 distances were measured. MEDAS software was used for performing connected and unconnected t-tests and Spearman´s rank correlation test to evaluate interrelations and differences.

Results

Orbital anatomy was highly symmetrical with a mean side difference of 0.3 mm for distances and 0.6° for angles. There was a small albeit statistically significant difference in 13 out of 155 distances in women and 1 in men concerning patients with and without EO. Two out of 12 angles showed a statistically significant difference between female patients with and without EO. Regarding sex, statistically significant differences occurred in 39 distances, orbit volume, orbit surface, and 2 angles. On average, measurements were larger in men. Concerning globe position within the orbit, larger distances to the orbital apex correlated with larger orbital dimensions whereas the sagittal position of the orbital rim defined Hertel values.

Conclusion

In this study, little difference in orbital anatomy between patients with and without EO was found. Concerning sex, orbital anatomy differed significantly with men presenting larger orbital dimensions. Regarding clinically measured exophthalmos, orbital aperture anatomy is an important factor which has to be considered in distinguishing between true exophthalmos with a larger distance between globe and orbital apex and pseudoexophthalmos were only the orbital rim is retruded. Thus, orbital anatomy may influence therapy regarding timing and surgical procedures as it affects exophthalmos.

[Orbital decompression : Indications, technique, results]

Orbital decompression is an effective surgical procedure to reduce intraorbital pressure. Causes may diseases leading to rapid pressure increases, e. g., bleedings, and those causing slower, progressive pressure increases, e. g., tumors or Graves' orbitopathy. During fat tissue decompression, peri- and retrobulbar adipose tissue is removed; in bony decompression, one or more bony orbital walls are removed (one-, two-, or three-wall decompression). In many cases the procedures are combined. Recent developments are the transconjunctival approaches for removing parts of bony orbital walls. Complications include double vision, which occurs in up to 30% of cases depending on the approach, hemorrhage, infections, development of chronic sinusitis, and iatrogenic skull base lesions with consecutive meningitis. In the hands of an experienced rhino- and head and neck surgeon, the intervention has low complication rates.

[Graves' ophthalmopathy]

Graves' orbitopathy (GO) is the main extrathyroidal manifestation of Graves' disease and the full clinical picture can impair the quality of life of the patients considerably. Active inflammation can often be effectively treated by intravenous steroids/immunosuppression, however does not lead to full remission, since inflammation rather quickly results in irreversible fibrosis and increase of orbital fat. Very important is the control of risk factors (smoking cessation, good control of thyroid function, selenium supplementation) to prevent progression to severe stages. Treatment should rely on a thorough assessment of activity and severity of GO. Rehabilitative surgery (orbital decompression, squint surgery, eyelid surgery) is needed in many patients to restore function and appearance. Anti-thyroid-stimulating hormone (TSH) receptor antibodies do specifically occur in these patients and correlate to the course of thyroid and eye disease. The levels of these antibodies can be used for treatment decisions at certain time points of the disease.

The Evolving Functions of Autophagy in Ocular Health: A Double-edged Sword

Autophagy plays an adaptive role in cell survival, development, differentiation and intracellular homeostasis. Autophagy is recognized as a 'self-cannibalizing' process that is active during stresses such as starvation, chemotherapy, infection, ageing, and oxygen shortage to protect organisms from various irritants and to regenerate materials and energy. However, autophagy can also lead to a form of programmed cell death distinct from apoptosis.

Components of the autophagic pathway are constitutively expressed at a high level in the eye, including in the cornea, lens, retina, and orbit. In addition, the activation of autophagy is directly linked to the development of eye diseases such as age-related macular degeneration (ARMD), cataracts, diabetic retinopathy (DR), glaucoma, photoreceptor degeneration, ocular tumours, ocular infections and thyroid-associated ophthalmopathy (TAO). A high level of autophagy defends against external stress; however, excessive autophagy can result in deterioration, as observed in ocular diseases such as ARMD and DR.

This review summarizes recent developments elucidating the relationship between autophagy and ocular diseases and the potential roles of autophagy in the pathogenesis and treatment of these diseases.