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ABSTRACT: AimsTo characterise and correlate crystalline precipitations implicated in non-healing corneal ulceration in two patients with a previous history of acanthamoeba keratitis.Materials and methodsPersistence of acanthamoeba and secondary bacterial infection was excluded with negative corneal scrapes. Confocal microscopy identified crystal-like deposits within the corneal stroma. To investigate possible precipitating combinations, all concurrent treatments at the time of presentation were mixed in wells, with observation of precipitate formation. Precipitates were observed with phase-contrast microscopy, and subsequently characterised via crystallography techniques and electrospray ionisation mass spectrometry.ResultsCombinations of dexamethasone 0.1% minims and chlorhexidine gluconate 0.2% formed an amorphous material characterised by electrospray ionisation mass spectrometry as an insoluble chlorhexidine salt. Combinations of chloramphenicol drops and timolol 0.5% formed a crystal identified via X-ray crystallography as santite (K(B5O6(OH)4).(H2O)2). This is a borate mineral identified in nature, arising from thermal springs, but never reported in biological tissues. Clinical improvement was observed following the cessation of the implicated precipitating combinations.Conclusion
Our observations suggest iatrogenic precipitate formation, with a potential deleterious effect upon healing. The substrates for these precipitates include several frequently prescribed topical ophthalmic treatments. These findings shed new light on the aetiopathogenesis of non-healing corneal ulceration, and have broad implications on topical prescribing for this challenging condition.Eye advance online publication, 5 April 2013; doi:10.1038/eye.2013.39.
Eye (London, England) 04/2013; · 1.97 Impact Factor
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Contact lens & anterior eye: the journal of the British Contact Lens Association 11/2012;
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ABSTRACT: Background/aimsThe purpose of this study was to critically evaluate the Catatrac device as a potential tool for rapid cataract screening in the developing world.Methods
Patients attending the day case unit at Gartnavel General Hospital for routine cataract surgery were recruited into the study, and divided into two groups: those with mild cataracts with LogMAR acuities <0.48, and those with advanced cataracts with LogMAR acuities ≥0.48. The subjects were examined without pharmacological dilation in a dimly lit room independently by two nurses. Each patient was then examined by an ophthalmologist with a slit lamp, after dilation. If present, cataracts were graded objectively according to the LOCS III classification system.ResultsOne hundred and twenty-two eyes of 73 patients were screened for the presence or absence of cataract using the Catatrac device. Thirty-nine eyes had mild cataracts, 43 eyes had advanced cataracts, and there were 40 control eyes with no cataracts. For detecting advanced cataracts, the two nurses using the Catatrac device had a specificity of 95.0%, a sensitivity between 86.0 and 93.0%, and κ values between 0.81 and 0.88 for agreement with slit lamp assessment. For detecting mild cataracts the two nurses using the Catatrac device again had a specificity of 95%, sensitivity of 71-84.6%, and κ values between 0.67 and 0.80 for agreement with slit lamp assessment. Interobserver agreement between the two nurses had a κ value of 0.61 for mild cataract and 0.74 for advanced cataract.Conclusion
The Catatrac device has a high specificity, sensitivity, and interobserver agreement for advanced cataracts. Although having a slightly lower sensitivity for mild cataracts, the authors believe that this study has demonstrated that it may be a low cost and easy to use device for rapid screening of visually significant cataracts in the developing world.Eye advance online publication, 26 October 2012; doi:10.1038/eye.2012.214.
Eye (London, England) 10/2012; · 1.97 Impact Factor
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ABSTRACT: Objective
To investigate the effect of temperature, dilution, and pH on the viscosity of ocular lubricants.DesignLaboratory based investigation of viscosity.ParticipantsNo human subjects.Methods
Hypromellose 0.3%, sodium hyaluronate 0.4%, carboxymethylcellulose sodium 0.5%/glycerin 0.9%, and carmellose sodium 0.5% were investigated. Ostwald capillary viscometers were utilised for viscosity measurements. The kinematic viscosity of each lubricant was tested quantitatively from 22 to 40 °C, and over a pH range of 5-8 under isothermal conditions. The kinematic viscosity of each eye drop was also tested under dilution by varying the mass fraction of each eye drop under isothermal conditions.Main outcome measureChanges in kinematic viscosity.ResultsHypromellose 0.3% had an initial pH of 8.34, while the other lubricants had a pH close to neutral. From 22 to 35 °C, the kinematic viscosity of sodium hyaluronate 0.4 fell by 36% from 37.8 to 24.4 mm(2)/s, carboxymethylcellulose sodium 0.5%/glycerin 0.9% fell by 35% from 16.98 to 11.1 mm(2)/s, hypromellose fell by 37% from 6.89 to 3.69 mm(2)/s, and carmellose sodium 0.5% fell by 25% from 2.77 to 1.87 mm(2)/s. At 32 °C only sodium hyaluronate 0.4%, and carboxymethylcellulose sodium 0.5%/glycerin 0.9% retained sufficient kinematic viscosity to maintain precorneal residence. Kinematic viscosities of all the topical lubricants were unaffected by pH but decreased significantly with dilution.Conclusions
This study suggests that currently used ocular lubricants have limited bioavailability due to reductions in viscosity by temperature and dilutional changes under physiological conditions. Developing lubricants with stable viscosities may maximise therapeutic efficacy.Eye advance online publication, 19 October 2012; doi:10.1038/eye.2012.211.
Eye (London, England) 10/2012; · 1.97 Impact Factor
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ABSTRACT: Matrix metalloproteinase-9 (MMP-9) secreted by corneal epithelial cells has a role in the remodelling of extracellular matrix and migration of epithelial cells. Elevated levels of MMP-9 activity in the ocular surface may be involved in the pathogenesis of corneal diseases. N-acetylcysteine (NAC) has been used to treat corneal diseases, including recurrent epithelial erosions. In this study, its effects on the MMP-9 secretion and human corneal epithelial (HCE) cell migration were evaluated in vitro.
Confluent HCE cell cultures were treated with 0-20 mM NAC, and tested for MMP-9 secretion and epithelial cell migration by gelatin zymography and scratch wound assay, respectively. Comparisons between different treatment groups were made using analysis of variance, followed by multiple pairwise comparisons.
Twenty mM NAC inhibited the secretion of MMP-9 significantly. Cell migration, assessed after 24 h of wounding, showed a highly significant dose-dependent inhibitory effect.
This study shows that NAC reduces MMP-9 production by HCE cells and inhibits cell migration in vitro. This information helps to elucidate the mechanisms by which NAC may be beneficial therapeutically and suggests that NAC may be useful for managing corneal erosions and related conditions.
Eye (London, England) 07/2012; 26(8):1138-44. · 1.97 Impact Factor
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ABSTRACT: To assess the agreement of the 'polygonal' variable frame cell count option on a confocal microscope after keratoplasty, with planimetry as the reference method.
One hundred clear corneal grafts of 83 patients attending the cornea clinic at Gartnavel General Hospital in Glasgow underwent slit-scanning in vivoconfocal microscopy. Endothelial cell images were assessed with the Nidek Advanced Vision Information System (NAVIS), using the polygonal variable frame and the manual fixed-frame methods. Planimetry was used as the reference. The agreement between methods was assessed by Bland-Altman analysis.
Planimetry provided a mean (± SD) endothelial cell density (ECD) of 1348 ± 726 cells/mm(2), a value that was very similar to that found by the polygonal method (1404 ± 784 cells/mm(2)). The fixed-frame method provided lower cell counts with a mean ECD of 1026 ± 610 cells/mm(2) (P<0.001). When compared with the reference ECD, the polygonal method overestimated the ECD only very slightly with a mean difference of 58 cells/mm(2) (limits of agreement, LoA, of -222 and 339 cells/mm(2)). Manual counting underestimated the ECD with a mean difference of -320 cells/mm(2) (LoA -814 and 173 cell/mm(2)).
Following keratoplasty, endothelial cell counts with the NAVIS polygonal method are in good agreement with planimetry. The 'polygonal' option is proposed as the method of choice for clinical applications with this confocal microscope and a good compromise between reliability and ease of use.
Eye (London, England) 03/2012; 26(6):803-9. · 1.97 Impact Factor
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ABSTRACT: Preservatives in ophthalmic preparations are known to cause ocular surface damage. Excipients can also contribute to oxidative stress in the compromised ocular surface. We evaluated commonly used topical glaucoma medications to ascertain pH levels and the intrinsic presence of free radicals.
Samples of 27 topical glaucoma preparations were analysed for total free radical presence using a Randox Kit for total antioxidant status. Analytical grade indicator paper was used to ascertain pH levels.
Free radical concentrations for these 27 glaucoma preparations ranged from 0 to 4.54 mmol/l, with a median value of 0.66 mmol/l (mean value of 0.662 mmol/l, SD 0.839). Levels of pH ranged from 4.0 to 7.4, with a median value of 6.5 (mean 6.252, SD 0.826). There was no evidence of a direct correlation between these two variables (r=0.232, P=0.275).
This study is the first to document the range of pH and concentrations of free radicals intrinsically present in commonly used glaucoma medications. Long-term exposure to preservatives, free radicals, and pH levels could all contribute to ocular surface damage. The effect of excipients could be responsible for patient intolerance when changing products in the compromised ocular surface.
Eye (London, England) 03/2012; 26(5):734-41. · 1.97 Impact Factor
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ABSTRACT: To review the indications and types of keratoplasty performed in the West of Scotland between 2001 and 2010.
A retrospective analysis of the histopathological diagnoses of all corneal buttons submitted to the regional Ocular Pathology Laboratory (Glasgow, UK) between January 2001 and December 2010 was performed.
Between 2001 and 2010, a total of 921 keratoplasties were performed in the West of Scotland. These included 646 (70.1%) penetrating keratoplasties and 275 (29.9%) lamellar keratoplasties (LK). Keratoconus (n=264, 28.7%) was the leading indication for keratoplasty, followed by graft failure (n=177, 19.2%), Fuch's endothelial dystrophy (n=124, 13.5%), keratitis (n=106, 11.5%), pseudophakic/aphakic bullous keratopathy (n=88, 9.6%), endothelial failure (n=67, 7.3%), non-Fuch's corneal dystrophies (n=21, 2.3%), trauma (n=19, 2.0%), autoimmune/inflammatory diseases (n=16, 1.7%) and others (n=39, 4.2%). A significant increase in the proportion of LK over penetrating keratoplasty was observed during this 10-year period: from 14.1% LK (2001-2005) to 40.4% LK (χ(2)=71.78, p value<0.001).
Keratoconus was the leading indication for keratoplasty in the West of Scotland. Both anterior LK and endothelial keratoplasty seemed to show an emerging trend as the procedures of choice for dealing with anterior and posterior corneal pathologies, respectively.
The British journal of ophthalmology 07/2011; 96(3):405-8. · 2.92 Impact Factor
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ABSTRACT: The purpose of this study was to assess the endothelium of corneal grafts by in vivo confocal microscopy (IVCM), and to evaluate an automated endothelial software system in comparison with a manual cell count and planimetry.
Overall, 40 corneal grafts (20 deep anterior lamellar keratoplasties (DALKs) and 20 penetrating keratoplasties (PKs)) were assessed by scanning-slit IVCM. The endothelial cell density (ECD) was estimated with the automated and the manual cell count method of the instrument's Nidek Advanced Vision Information System (NAVIS) software. The results were compared with planimetry as the reference method, and the agreement was assessed.
The mean (±SD) automated ECD was 2278±524 cells/mm(2) (range 1167-3192 cells/mm(2)), whereas the manual cell count method gave significantly lower ECDs with a mean of 1213±677 cells/mm(2) (range 218-2440 cells/mm(2); P<0.001). The manual cell counts were also significantly lower than those by planimetry, with a mean ECD of 1617±813 cells/mm(2) (range 336-2941, P<0.001). Bland-Altman analyses indicated that the limits of agreement (LoA) between the automated and the planimetry method were -671 and +1992 cells/mm(2), whereas they were -1000 and +202 cells/mm(2) when comparing the manual cell counts with planimetry.
Following keratoplasty, the NAVIS automated method is likely to overestimate endothelial cell counts due to oversegmenting of the cell domains. Automated ECDs are substantially higher than those by the manual counting method or planimetry. The differences are considerably larger post-keratoplasty than for normal corneas, and the methods should not be used interchangeably.
Eye (London, England) 06/2011; 25(9):1130-7. · 1.97 Impact Factor
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ABSTRACT: To report the histopathological changes occurring in the cornea in sympathetic ophthalmitis.
Observational case series of 3 patients with sympathetic ophthalmitis who were treated with penetrating keratoplasty. We report the histopathological features of the cornea.
In all 3 cases, the epithelium was edematous and bullous with extensive loss of the Bowman layer and calcification of the superficial stroma in all the 3 eyes. The deep stroma was unremarkable in appearance. Descemet membrane showed thickening in 2 of the corneas with nodular excrescences and folds noted in 1 of the specimens. The endothelium was attenuated with some residual cells containing pigment granules in 1 case.
Endothelial loss and development of bullous keratopathy associated with band keratopathy are predominate histopathological features of the cornea. These changes are nonspecific and reflect a chronic anterior uveitis.
Cornea 11/2010; 29(11):1287-90. · 1.73 Impact Factor
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ABSTRACT: To determine the visual outcome, graft survival and complications after deep anterior lamellar keratoplasty (DALK) in patients with herpes simplex virus (HSV)-related corneal scarring.
A retrospective analysis of the patients who had DALK for HSV-related corneal scarring between January 2004 and February 2007 was performed. Mean follow-up was 30 months (range 16-48 months). The statistical significance of host corneal vascularisation was determined using Fisher's exact test.
There were 18 eyes from 18 patients and the mean age was 57 years. Preoperative visual acuity ranged from hand movements (HM) to 6/12. Fifty per cent of the eyes achieved visual acuity of 6/12 or better postoperatively. Six eyes (33%) had recurrence of HSV-related inflammation, eight eyes (including four eyes with recurrence of HSV-related inflammation) developed graft rejection and four eyes (including two eyes with recurrence of HSV-related inflammation) had bacterial keratitis. The graft survival rate was 83%. Three eyes developed glaucoma and one eye required trabeculectomy. Immunohistochemistry revealed that HSV was focally positive or equivocal in four recipient corneal buttons, and transmission electron microscopy showed intracellular HSV virions in two of them.
This is the largest series of DALK for herpetic corneal scarring that shows a comparable visual outcome and better graft survival rate than penetrating keratoplasty. There is significant risk of recurrence of HSV-related inflammation and graft rejection that requires timely recognition and adequate management.
The British journal of ophthalmology 10/2010; 94(10):1300-3. · 2.92 Impact Factor
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ABSTRACT: The purpose of this case series was to evaluate the effectiveness of modified deep anterior lamellar keratoplasty in eyes with scarring secondary to hydrops associated with keratoconus.
Four patients underwent modified deep anterior lamellar keratoplasty. This was performed by controlled air injection and layer-by-layer dissection of the corneal stroma. The corneal stroma was dissected up to 95% thickness using a Beaver blade. The host Descemet membrane (DM) (4 mm in diameter) that was incorporated in the scar was excised. The DM and the endothelium from the donor button were removed, and the graft was applied to the recipient bed. Twenty percentage sulfur hexafluoride gas was injected to tamponade the host DM to the donor cornea. The graft was sutured with 10-0 monofilament nylon. An amniotic membrane dressing was applied.
The preoperative visual acuity was between counting fingers to 6/36. Six weeks postoperatively, the grafts were clear. At 1-year follow-up, the best-corrected visual acuity was 6/12 or better in all patients.
Modification of deep anterior lamellar keratoplasty may be an effective alternative to penetrating keratoplasty in eyes with corneal scarring because of previous hydrops.
Cornea 10/2010; 30(2):180-3. · 1.73 Impact Factor
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The British journal of ophthalmology 01/2010; 94(1):136-7. · 2.92 Impact Factor
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ABSTRACT: To report a case of deep anterior lamellar keratoplasty (DALK) on a previously failed full-thickness graft in a case of herpetic keratitis.
A 70-year-old patient with a history of penetrating keratoplasty for herpetic keratitis performed 30 years ago presented with blurry vision in her left eye. She had corneal stromal scarring secondary to herpetic keratitis. The endothelium was spared. We performed a DALK with big-bubble technique.
Postoperatively, corneal edema was noticed initially, which resolved in 3 months. Her best-corrected visual acuity is 6/12 in her left eye.
DALK on a previous penetrating keratoplasty is a technical possibility when there is a functioning endothelium.
Cornea 06/2009; 28(4):456-7. · 1.73 Impact Factor
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Eye (London, England) 04/2009; 24(1):200-1. · 1.97 Impact Factor
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ABSTRACT: To describe an alternative and novel technique using cyanoacrylate glue to achieve successful limbal tissue dissection, from an organ culture media stored corneoscleral button, without an artificial anterior chamber.
A donor corneoscleral button (leftover from penetrating keratoplasty) was divided into two equal semicircular halves. A thick layer of tissue adhesive (N-butyl-2-cyanoacrylate) was spread on a sterile rubber block (the under surface of the donor punch). One half of the donor corneoscleral rim was placed epithelial side up on the adhesive and allowed to attach firmly to the block. This composite provided stability to the donor rim allowing lamellar dissection of the limbal tissue to be performed without damaging the limbal epithelium.
Regular, partial-thickness limbal tissue was obtained. There was no histological evidence of glue or cellular toxicity of the harvested limbal stem cells. This harvested tissue had been grafted successfully in patients with limbal stem cell deficiency also undergoing keratoplasty.
Tissue adhesive can be a simple, effective and useful tool in the dissection and harvesting of corneal limbal stem cell allografts from corneoscleral buttons stored in organ culture media.
The British journal of ophthalmology 12/2008; 92(11):1550-1. · 2.92 Impact Factor
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Eye (London, England) 11/2008; 23(7):1605. · 1.97 Impact Factor
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ABSTRACT: To report two cases of young diabetic patients with intractable neovascular glaucoma (NVG) who were successfully managed with bevacizumab and mitomycin C-augmented trabeculectomy.
Two young patients present with severe NVG secondary to diabetic proliferative retinopathy. The glaucoma was unresponsive to conventional medical therapy and complete panretinal photocoagulation. Both patients underwent augmented trabeculectomy with MMC and intravitreal injection of bevacizumab. Iris rubeosis resolved within 48 h. Both patients have a follow-up period of 6 months and the intraocular pressure (IOP) remain between 10-15 mmHg.
Controlling IOP due to NVG in young diabetic patients is difficult and augmented trabeculectomy has a very high failure rate. The addition of intravitreal bevacizumab in the management of NVG particularly in young diabetic patients may improve the success rate of IOP control. It is known that bevacizumab retards neovascularisation. It may also be modulating wound-healing response as well. Bevacizumab may have a potential role in the surgical management of NVG.
Eye (London, England) 06/2008; 23(4):979-81. · 1.97 Impact Factor
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ABSTRACT: We report the incidence, causes, characteristics, and the outcome of traumatic corneal graft ruptures in a tertiary referral centre in the UK.
A retrospective analysis of all graft ruptures secondary to trauma that were treated at our centre between 1999 and 2005 was undertaken. Statistical analysis of possible prognostic factors was undertaken using the Fisher's test.
Nineteen eyes in 18 patients sustained eye trauma resulting in graft rupture (median age of 53 years; range 27-82; 15 men and four women). Seventeen cases were accidental and two were from violence. The median time interval between grafting and rupture was 8.3 months (range 3 days to 15 years). The 6-year incidence was 3.8%. All graft ruptures occurred at the host-graft junction and ranged from 45 to 270 degrees . Iris prolapse/loss was noticed in 89% and lens loss in 53%. The most common posterior segment complication was vitreous loss (74%), followed by vitreous haemorrhage (32%) and retinal detachment (21%). Grafts with 180 degrees or more of dehiscence were more likely to fail (P<0.001), had more extensive posterior segment damage, and a poorer visual outcome. Grafts without sutures had a more extensive dehiscence (P<0.01). Final visual acuity was worse than 6/60 in 58%.
The risk of traumatic corneal graft rupture is significant and is associated with a poor visual outcome. This fact needs to be clearly emphasised during preoperative counselling and protective measures encouraged.
Eye 10/2007; 21(9):1146-50. · 1.85 Impact Factor
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ABSTRACT: Corneal perforation can be potentially blinding unless the integrity of the globe is restored quickly. Although penetrating keratoplasty (PK) may achieve this, it carries a high risk of endothelial rejection in inflamed eyes. Deep lamellar keratoplasty (DLK) may be an alternative option to PK in such eyes owing to its potential for a lower incidence of rejection. We report the efficacy of DLK in patients with corneal perforations.
Four patients underwent layer-by-layer DLK for noninfective corneal perforation, after measures such as the use of a bandage contact lens, tissue adhesive, and conjunctival pedicle flap had failed. The preoperative visual acuity was hand movements in one patient, 1/60 in two, and 6/60 in one. All four had iris incarcerated within the corneal perforations. SF6 gas (three patients) and air (one patient) were injected into the anterior chamber at the end of surgery.
The integrity of the globe was restored in all four patients with an improvement in visual acuity (6/60 in one and 6/36 or better in three). The mean follow-up time was 7 months. All four patients had clear corneas 3 months postoperatively, apart from the area of the original perforation. There was no recurrence of ulceration or perforation.
DLK is a safe and effective therapeutic measure in the management of patients with corneal perforations acting to preserve the integrity of the globe and restore vision.
Eye 10/2007; 21(9):1168-73. · 1.85 Impact Factor
