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Corneal nerves are key components of the physiological system that controls ocular surface homeostasis. The cornea is primarily innervated by the ophthalmic branch of the trigeminal nerves (cranial nerve V), which distend bilaterally from the pons. The nasociliary branch (afferent) of the ophthalmic nerve is sensory for cornea, eyelid and conjunctiva. These nerve fibres play a role in sensing temperature, chemical and mechanical stimuli, and pain, whereas, branches of the facial nerve (cranial nerve VII) contain motor nerves that control blinking and autonomic (sympathetic and a paucity of parasympathetic) fibres that stimulate tear production and secretion via feedback loops between the ocular surface, lacrimal glands and brain. Disruption of these nerves with interruption of neural feedback loops between the ocular surface and lacrimal glands can lead to corneal diseases such as dry eye disease (DED) and neurotrophic keratopathy (NK). Inversely, hypersensitivity of the nerve fibres and/or dysregulation of pain-controlling nervous centres may lead to neuropathic pain. Recently, medications that specifically target regeneration of corneal nerves have started to become available - and considering the high prevalence of diseases associated with corneal nerve dysfunction, these agents promise to fulfil a hitherto important unmet need. In this review, we explore the physiology of corneal nerves, the pathology of corneal nerve diseases and how these relate to neuropathic pain, NK and DED. We also discuss what novel treatments may be useful against diseases involving corneal nerves.

Objective To describe a clinical entity of upper eyelid margin and meibomian gland inversion (MGI) sequential to meibomian gland dysfunction (MGD), in the absence of eyelash ptosis, trichiasis or manifest marginal entropion. We highlight its clinical features, surgical management and outcomes. Methods We performed a retrospective analysis of symptomatic MGI cases refractory to conservative management who underwent surgery in our centre over a 4-year period. Anatomical correction, resolution of symptoms and possible complications are reported. Results A total of 21 eyelids of 13 patients (mean age: 68.5 ± 15.4, range: 32-88 years) were analysed. Symptomatic MGI patients were operated only if they have noted immediate comfort when we corrected the lid margin position with a cotton tip. Those with refractory superior punctate corneal staining (n = 14 eyes), blink-related discomfort (n = 8) and pseudo-blepharospasm (n = 3) reported complete postoperative resolution. Milder symptoms showed partial improvement: gritty feeling (79%), sore eye (80%) and watery eye (86%). However, symptoms of dry eye disease (DED) persisted in 88% of patients. One case recurred in 6 weeks and was offered revision surgery. Median follow-up was 5 (range: 3-12) months. Conclusion Meibomian gland inversion (MGI) is a subtle clinical entity that can be easily overlooked. Symptoms are often attributed to DED or MGD alone. It is likely that MGI represents early upper lid margin anatomical changes secondary to MGD before cicatricial marginal entropion becomes clinically apparent. Recommended treatment is conservative with intensive lid hygiene and topical MGD management. However, refractory symptomatic cases who respond positively to a 'cotton-tip test' (reversal of lid margin malposition with a rolling cotton-tip) may benefit from surgical intervention with favourable anatomical and functional outcome.

Background Orbital decompression is an established procedure for the management of exophthalmos and visual rehabilitation from optic neuropathy in cases of thyroid eye disease. Numerous procedures for removal of orbital bony wall, fat or a combination of these for a variety of indications in different stages of the disease have been well reported in the medical literature. However, the relative effectiveness and safety of these procedures in relation to the various indications remains unclear. Objectives To review current published evidence for the effectiveness of surgical orbital decompression for disfiguring proptosis in adult thyroid eye disease and summa rise information on possible complications and the quality of life from the studies identified. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 October 2011. We searched oculoplastic textbooks, conference proceedings from the European and American Society of Ophthalmic Plastic and Reconstructive Surgery (ESOPRS, ASOPRS), European Ophthalmological Society (SOE), the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) for the years 2000 to 2009 to identify relevant data. We attempted to contact researchers who are active in this field for information about further published or unpublished studies. Selection criteria We included randomised controlled trials (RCTs) with no restriction on date or language comparing two or more surgical methods for orbital decompression with removal of bony wall, orbital fat or a combination of both for disfiguring proptosis or comparison of surgical techniques with any form of medical decompression. Data collection and analysis Each review author independently assessed study abstracts identified from the electronic and manual searches. Author analysis was then compared and full papers for appropriate studies were obtained according to the inclusion criteria. Disagreements between the authors were resolved by discussion. Main results We identified two randomised trials eligible for inclusion in the review. There was significant variability between the trials for interventions, methodology and outcome measures and therefore meta-analysis was not performed. One study suggested that the transantral approach and endoscopic transnasal technique had similar effects in reducing exophthalmos but that the endoscopic approach may be safer, relating to fewer complications. This study had short-term follow-up and lacked information on our primary outcome (success or failure of treatment). The second study provided evidence that intravenous steroids may be superior to primary surgical decompression in the management of compressive optic neuropathy requiring less secondary surgical procedures, although it relates more frequently to transient side effects. This study was weakened by a small sample size. Until more credible evidence is available recommendations as to best treatment cannot be reliably made. Authors' conclusions A single study showed that the transantral approach for orbital decompression was related to more complications than the endoscopic transnasal technique which is preferred by Ear, Nose and Throat (ENT) surgeons, usually as an adjunctive procedure. Intravenous steroids were reported in a single trial to be the most efficient intervention for dysthyroid optic neuropathy. The majority of published literature on orbital decompression for thyroid eye disease consists of retrospective, cohort, or case series studies. Although these provide useful descriptive information, clarification is required to show the relative effectiveness of each intervention for various indications. The two RCTs reviewed are not robust enough to provide credible evidence to our understanding of current decompressive surgery and to support recommendations for clinical practice. There is evidence from currently available uncontrolled studies that removal of the medial and lateral wall (balanced decompression) with or without fat removal may be the most effective surgical method related to only a few complications. There is a clear need for randomised studies evaluating the balanced two-wall, three-wall and orbital fat decompression techniques. Comparison with other surgical techniques for orbital decompression or with immunosuppression in cases of compressive optic neuropathy would also be important. These studies should primarily address the reduction of exophthalmos, disease severity, complication rates, quality of life and cost of the intervention.