Mark McCombe

Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia

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Publications (12)19.41 Total impact

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    ABSTRACT: Retinal visual prostheses ("bionic eyes") have the potential to restore vision to blind or profoundly vision-impaired patients. The medical bionic technology used to design, manufacture and implant such prostheses is still in its relative infancy, with various technologies and surgical approaches being evaluated. We hypothesised that a suprachoroidal implant location (between the sclera and choroid of the eye) would provide significant surgical and safety benefits for patients, allowing them to maintain preoperative residual vision as well as gaining prosthetic vision input from the device. This report details the first-in-human Phase 1 trial to investigate the use of retinal implants in the suprachoroidal space in three human subjects with end-stage retinitis pigmentosa. The success of the suprachoroidal surgical approach and its associated safety benefits, coupled with twelve-month post-operative efficacy data, holds promise for the field of vision restoration. Clinicaltrials.gov NCT01603576.
    PLoS ONE 12/2014; 9(12):e115239. · 3.53 Impact Factor
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    ABSTRACT: Current surgical techniques for retinal prosthetic implantation require long and complicated surgery, which can increase the risk of complications and adverse outcomes. The suprachoroidal position is known to be an easier location to access surgically, and so this study aimed to develop a surgical procedure for implanting a prototype suprachoroidal retinal prosthesis. The array implantation procedure was developed in 14 enucleated eyes. A full thickness scleral incision was made parallel to the intermuscular septum and superotemporal to the lateral rectus muscle. A pocket was created in the suprachoroidal space and the moulded electrode array inserted. The scleral incision was closed and scleral anchor point sutured. In 9 of the 14 eyes examined, the device insertion was obstructed by the posterior ciliary neurovascular bundle. Subsequently we characterised the position of this neurovascular bundle in 10 eyes. Implantation and lead routing procedure was then developed in 6 human cadavers. The array was tunnelled forward from behind the pinna to the orbit. Next a lateral canthotomy was made. Lead fixation was established by creating an orbitotomy drilled in the frontal process of the zygomatic bone. The lateral rectus muscle was detached and implantation carried out. Finally, pinna to lateral canthus measurements were taken on 61 patients in order to determine optimal lead length. These results identified potential anatomical obstructions and informed the anatomical fitting of the suprachoroidal retinal prosthesis. As a result of this work a straight forward surgical approach for accurate anatomical suprachoroidal array and lead placement was developed for clinical application.
    Clinical and Experimental Ophthalmology 09/2014; · 1.95 Impact Factor
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    ABSTRACT: Our research goal is to develop a safe, reproducible surgical approach for implantation of a wide-field retinal stimulating array. The aim of this study was to evaluate the pathological response to acute implantation of a functional prototype electrode array in the suprachoroidal space. The surgical techniques to implant a 72 platinum electrode array fabricated on 8 × 13 × 0.4 mm polyimide and silicone substrate were developed in a pilot study in anesthetized cats. For the main study, nine eyes were implanted in vivo and unoperated eyes were used as controls. Surgery consisted of a temporal approach with a full-thickness scleral incision 5 mm posterior to the limbus. A suprachoroidal "pocket" was created, the electrode array inserted to sit beneath the area centralis, and placement was confirmed visually. The eyes were collected subsequently for histopathology. The array was consistently inserted into the suprachoroidal space beneath the area centralis in nine eyes. There was a significant hemorrhage in two cases where implantation was complicated by choroidal congestion. Retinal folding occurred only when the array tip was within 2.6 mm of the optic disc (p < 0.01). There was choroidal incarceration at the incision in six eyes and scleral distortion at the array edges in five. No cases were found where the implant breached the retina, choroid, or sclera. A large stimulation array can be reliably inserted into the suprachoroidal space without trauma to the neuroretina. These findings suggest that this is an appropriate surgical approach for the placement of an electrode array for use in retinal stimulation.
    Albrecht von Graæes Archiv für Ophthalmologie 08/2011; 250(3):399-407. · 1.93 Impact Factor
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    ABSTRACT: Endogenous endophthalmitis (EE) is a sight-threatening emergency and the aetiology is often multifactorial. Delayed diagnosis may exacerbate the poor visual prognosis. We describe the management and visual outcomes of EE presenting to a tertiary referral centre. A prospective consecutive case series of 64 patients presenting with presumed EE from 1997 to 2007 to the Royal Victorian Eye and Ear Hospital were included. All data were collected in a standardized manner. Outcome measures included: visual acuity, microbial profiles, and vitrectomy rate. In total, 64 cases of EE were identified over the study period with a mean age of 57.5 years, and 53.5% were male. Presenting acuities ranged from Snellen 6/6 to no perception of light (NPL). Identifiable risk factors were present in 78.1%, with the majority related to intravenous drug abuse. A 64.1% culture positivity rate was recorded. A vitrectomy rate of 57, 56, and 21% was recorded in documented bacterial, fungal, and no growth cases, respectively. Final Snellen acuities ranged from 6/6 to NPL. A total of 5 out of 64 eyes were enucleated, of which 3 identified Klebsiella species. Better visual outcome was documented in fungal cases. EE is a serious ocular condition and has a varied aetiology. Visual outcomes are often poor, irrespective of the method of management. Fungal aetiology often confers a better prognosis, and vitrectomy is advocated for bacterial proven cases.
    Eye (London, England) 10/2010; 25(1):66-72. · 1.97 Impact Factor
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    ABSTRACT: Bevacizumab (Avastin) is a monoclonal antibody which targets all isoforms of vascular endothelial growth factor A. Its potent anti-angiogenic effects have been shown to cause regression of neovascularization in proliferative diabetic retinopathy. The aim of this study is to investigate the role of Avastin as an adjunct to vitrectomy in the management of severe diabetic eye disease. Sixteen patients (18 eyes) with severe proliferative diabetic retinopathy were recruited into the study. All eyes underwent a single intravitreal injection of bevacizumab 1.25 mg in 0.05 mL prior to vitrectomy surgery for the management of tractional retinal detachment or vitreous haemorrhage due to severe proliferative diabetic retinopathy. At 3 months, seven eyes had visual acuities which were better than baseline, four were unchanged and seven were worse. At 6 months, 14 eyes had visual acuities better than baseline, one was unchanged and three were worse. Seven of the 18 eyes (38.8%) had postoperative rebleeds, six of which required surgical washout. Avastin improved the ease of the surgery in these complex eyes and the early results are encouraging. We have found it to be particularly useful in diabetic eyes with traction detachments of short duration in which there is still active neovascularization.
    Clinical and Experimental Ophthalmology 08/2008; 36(5):449-54. · 1.95 Impact Factor
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    ABSTRACT: Purpose: To describe the optical coherence tomography (OCT) findings in two patients with welder's maculopathy. Methods: Retrospective cases series. In addition to examination by slit lamp biomicroscopy, color fundus photographs and OCT images were obtained from patients with welder's maculopathy. Results: Both patients had a history of bilateral decreased central vision after welding without appropriate eye protection. Yellowish foveal spots developed in the acute stage, evolving over several months into well demarcated lamellar foveal defects with surrounding retinal pigment epithelium changes. OCT showed interruption of the inner high reflective layer (HRL) corresponding to the level of the outer neurosensory retina. These appearances are similar to those seen in solar maculopathy. Conclusions: OCT shows disruption of the inner HRL in late welder's maculopathy. These appearances are similar to those seen in late solar maculopathy. OCT can be a useful tool in confirming the diagnosis and understanding the pathogenesis of photic maculopathy.
    Retinal Cases & Brief Reports 12/2006; 1(3):169-171.
  • Clinical and Experimental Ophthalmology 05/2006; 34(4):388-90. · 1.95 Impact Factor
  • Retina 01/2003; 22(6):815-8. · 3.18 Impact Factor
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    ABSTRACT: Purpose: To evaluate the advantages and disadvantages of the retention and removal of silicone oil in the treatment of complicated retinal detachments.Methods: The records of 344 patients (348 eyes) that underwent vitrectomy and silicone oil injection for complicated retinal detachments were abstracted and analysed. The anatomical and functional results, complications and influencing factors are discussed. The outcome in eyes after removal of the silicone oil was compared with the outcome in a comparable group of eyes in which the silicone oil was retained.Results: The overall retinal reattachment rate was 63% (220/348). The final vision of 5/300 or better was 52% (115/220) in those eyes with totally attached retinas. The silicone oil-related complications included keratopathy (23%) and secondary glaucoma (11%). Comparing removal of silicone oil with retention of silicone oil, we found: (i) there was no statistical difference in the redetachment rate (19 vs 17%); (ii) Oil-removed eyes had a better final vision (P < 0.05); and (iii) keratopathy (13 vs 23%), secondary glaucoma (11 vs 25%) and optic nerve atrophy (4 vs 18%) were significantly lower in oil-removed eyes.Conclusion: Silicone oil injection is useful in the treatment of complicated retinal detachments. For reducing the incidence of complications, early removal of silicone oil is recommended in those cases in which the retina is attached, all breaks adequately closed and traction relieved.
    Australian and New Zealand Journal of Ophthalmology 10/1998; 26(4):299 - 304.
  • Mark McCombe, Wilson Heriot
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    ABSTRACT: A series of 13 cases of globe perforation following local ocular anaesthesia are reported. All cases were associated with cataract surgery. Perforation occurred with the retrobulbar approach in nine cases and with the peribulbar approach in two cases. In two cases the approach for local anaesthesia was not recorded. In 12 of the 13 cases, a perforating wound was found in the inferotemporal quadrant. All cases were found to have vitreous haemorrhage. All cases had significant posterior segment injury. Vitrectomy was carried out in nine of the 13 cases. At final review the retina was attached in 12 of the 13 cases. A final visual acuity of between 6/9 and 6/12 was achieved in six cases, four cases had acuity of between 6/18 and 6/24 and three cases had a visual result of less than 6/60.
    Australian and New Zealand Journal of Ophthalmology 03/1995; 23(1):33-6.
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    ABSTRACT: Intravenous drug use (IVDU) is a known risk factor for endogenous endophthalmitis. Endogenous fungal endophthalmitis (EFE) is emerging as a common problem among this community. We describe the management and visual outcomes of acute IVDU-associated EFE. A prospective consecutive case series of 19 patients presenting with presumed acute IVDU-associated EFE from 2001 to 2007 to the Royal Victorian Eye and Ear Hospital was included. All data were collected in a standardized manner. Outcome measures included visual acuity, microbial profiles, and vitrectomy rate. Nineteen cases of IVDU-associated EFE were identified. Eight of these (42%) were men, and the mean age was 32.7 years (SD ± 8.0 years). Presenting visual acuity ranged from 6/6 to perception of light, with 58% having a visual acuity of 6/48 or less at presentation. Thirteen (68.4%) were culture positive with all cultures identifying Candida species, and 52.7% underwent vitrectomy. Fifty percent of subjects overall achieved a final visual acuity of 6/18 or better. Men demonstrated improved visual acuity when compared with women (P = 0.04). Age had no effect on final acuity. Intravenous drug use is a significant risk factor for developing EFE. Good visual outcomes can be achieved with early treatment, often with intravitreal therapy alone.
    Retina (Philadelphia, Pa.) 30(10):1721-5. · 2.93 Impact Factor