K Ramaesh

Glasgow Caledonian University, Glasgow, SCT, United Kingdom

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Publications (91)201.1 Total impact

  • David Lockington, Kanna Ramaesh
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    ABSTRACT: We describe a novel surgical technique that seeks to address the fundamental mechanical problem of the superiorly and vertically displaced limbus and the corresponding abnormal corneal white-to-white diameter in keratoglobus. A 42-year-old woman had progressive reduction of vision due to hydrops of her right cornea with secondary peripheral corneal perforation due to progressive bilateral keratoglobus. Her visual acuity was hand movements in the right eye, with an uncorrectable refractive error. Pachymetry ranged from 287 μm in the peripheries to 474 μm centrally. The simulated keratometry average was 87 diopters. The surgical technique includes corneal debridement, paracentesis to facilitate manipulation of the cornea, cardinal compression sutures, central anterior lamellar dissection, and mattress sutures to tuck the excess peripheral cornea to create a pleat. This intralamellar tuck formed the subsequent bed to host an anterior lamellar corneal graft. At 1-year review, the best-corrected visual acuity was 6/24 (-2.50/+2.00 ×75 in the right eye). Central corneal pachymetry was 744 μM in the right eye. The simulated keratometry average was 42.4 diopters. This visual improvement and refraction remained stable for 3 years postoperatively. We have demonstrated a modified anterior lamellar keratoplasty with pleat technique to achieve satisfactory visual rehabilitation in extreme keratoglobus. This pleat technique addresses the fundamental structural problem of a vertically displaced limbus in keratoglobus. We highlight the optical illusion of the white-to-white diameter in keratoglobus. We also recommend the baking analogy of muffin to cupcake as a communication aid when explaining the mechanics of surgery to the patient.
    Cornea 12/2014; · 1.75 Impact Factor
  • Clinical and Experimental Ophthalmology 10/2014; · 1.96 Impact Factor
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    ABSTRACT: Objet La membrane amniotique (MA) sert à gérer divers états de débilitation des surfaces oculaires. La reconnaissance de l’impact du stress oxydant et des radicaux libres sur la surface oculaire augmente. L’acide hyaluronique (AH) a des propriétés anti-inflammatoires et abonde dans la MA. Dans cette étude pilote in vitro, nous avons examiné le potentiel de la MA concernant ses propriétés anti-radicalaires intrinsèques. Nature Étude pilote in vitro. Méthodes Des bandes de MA ont été incubées dans des tubes scellés avec de l’eau oxygénée (H2O2). Après la soumission à l’ultrason, la prise des dérivés réactifs d'oxygène (DRO) a été mesurée par le test Amplex de peroxyde/peroxydase d’hydrogène rouge. L’AH de 1630kDA a servi à la comparaison. Résultats Il y eut des prises des DRO dans tous les échantillons de MA, qui diminuèrent avec l’augmentation des concentrations de H202. La moyenne des prises des DRO de 5 MA différentes après 1 heure était considérablement plus grande pour 50uM (83 %; SD 11,7, SEM 5,23) comparativement à 100uM (67 %; SD 20,48, SEM 9,16; p = 0,028, 95% CI (2,8, 29,2)). La comparaison du groupe AH a montré une prise et une tendance similaires. Conclusion Cette étude pilote démontre que la MA peut éliminer les DRO de son environnement. La démonstration de l’entière capacité antioxydante de l’AM fournit l’évidence de son utilisation comme puissant anti-radicalaire. Les propriétés d’antioxydant de la MA et la contribution de l’AH requièrent plus de recherches.
    Canadian Journal of Ophthalmology / Journal Canadien d'Ophtalmologie. 10/2014; 49(5):426–430.
  • Clinical and Experimental Ophthalmology 07/2014; · 1.96 Impact Factor
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    ABSTRACT: It has been suggested that the isolation of scalable populations of limbal stem cells may lead to radical changes in ocular therapy. In particular, the derivation and transplanta-tion of corneal stem cells from these populations may result in therapies providing clinical normality of the diseased or damaged cornea. Although feasible in theory, the lack of donor material in sufficient quantity and quality currently limits such a strategy. A potential scalable source of corneal cells could be derived from pluripotent stem cells (PsCs). We developed an in vitro and serum-free corneal differentiation model which displays significant promise. Our stepwise differentiation model was designed with reference to development and gave rise to cells which displayed similarities to epithelial progenitor cells which can be specified to cells displaying a corneal epithelial phenotype. We believe our approach is novel, provides a robust model of human development and in the future, may facilitate the generation of corneal epithelial cells that are suitable for clinical use. Additionally, we demonstrate that following continued cell culture, stem cell-derived corneal epithelial cells undergo transdifferentiation and exhibit squamous metaplasia and therefore, also offer an in vitro model of disease.
    International Journal of Molecular Medicine 03/2014; 33:429-125840. · 1.96 Impact Factor
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    ABSTRACT: It has been suggested that the isolation of scalable populations of limbal stem cells may lead to radical changes in ocular therapy. In particular, the derivation and transplantation of corneal stem cells from these populations may result in therapies providing clinical normality of the diseased or damaged cornea. Although feasible in theory, the lack of donor material in sufficient quantity and quality currently limits such a strategy. A potential scalable source of corneal cells could be derived from pluripotent stem cells (PSCs). We developed an in vitro and serum-free corneal differentiation model which displays significant promise. Our stepwise differentiation model was designed with reference to development and gave rise to cells which displayed similarities to epithelial progenitor cells which can be specified to cells displaying a corneal epithelial phenotype. We believe our approach is novel, provides a robust model of human development and in the future, may facilitate the generation of corneal epithelial cells that are suitable for clinical use. Additionally, we demonstrate that following continued cell culture, stem cell-derived corneal epithelial cells undergo transdifferentiation and exhibit squamous metaplasia and therefore, also offer an in vitro model of disease.
    International Journal of Molecular Medicine 03/2014; · 1.96 Impact Factor
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    ABSTRACT: PurposeXerophthalmia refers to the ocular manifestations associated with vitamin A deficiency, including xerosis, keratomalacia, nyctalopia and Bitot's spot. Hypovitaminosis A is well-recognised in developing countries, but is rare in the developed world. Most cases in the latter relate to fat malabsorption. Conditions in which vitamin A metabolism or storage is deranged (chronic liver disease, including alcoholism) are also aetiologies. We wanted to see whether this was common in our department.Methods Oral vitamin A supplements were given to patients who presented with hypovitaminosis A.ResultsAll patients were found to have hypovitaminosis A on biochemical testing and responded dramatically to oral vitamin A supplementation, resulting in an improved final visual outcome.DiscussionThis series demonstrates that prompt recognition and treatment of xerophthalmia can lead to rapid recovery and avert significant visual morbidity. The prevalence of xerophthalmia is likely to increase in the developed world largely owing to alcoholic liver disease. It is thought by some that we are on the verge of a potential epidemic. We hope that by increasing the profile of this important public health issue, we may be able to influence future prevalence of hypovitaminosis.Eye advance online publication, 14 February 2014; doi:10.1038/eye.2014.17.
    Eye (London, England) 02/2014; · 1.97 Impact Factor
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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
  • S. Tarafdar, S. Ramamurthi, K. Ramaesh
    Contact lens & anterior eye: the journal of the British Contact Lens Association 04/2013; 36(2):101–102.
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    ABSTRACT: BACKGROUND: The aim was to assess the corneal endothelium, post-operative visual outcome and complications following keratoplasty for keratoconus. METHODS: Seventy-six corneal grafts (57 per cent penetrating keratoplasties and 43 per cent deep anterior lamellar keratoplasties) were assessed as part of routine follow-up at the Ophthalmology Department at Gartnavel General Hospital in Glasgow. Routine ophthalmic assessment included visual acuity, slitlamp biomicroscopy and scanning slit confocal microscopy of the central cornea. Case records were reviewed and demographic, surgical and post-operative data retrieved. Linear and logistic regression models were used to determine associations between endothelial cell density, visual acuity and post-operative complications. Kaplan-Meier analysis was used to estimate the probability for grafts to retain more than 700 endothelial cells per mm(2) and to have 0.3 logMAR or better vision. Odds ratios were calculated to assess the risk for low cell counts and poor visual outcome. RESULTS: The mean and standard deviation of the endothelial cell count was predictably higher in lamellar (2033 ± 643 cells per mm(2) ) than penetrating keratoplasties (898 ± 380 cells per mm(2) ) and the mean post-operative cell count for grafts without post-operative complications was higher (1585 ± 775) than those with complications (1312 ± 747 cells per mm(2) ). Mean visual acuity was 0.25 ± 0.20 and 0.29 ± 0.41 for lamellar and penetrating keratoplasties, respectively. A higher number of post-operative events was associated with an increased risk for graft rejection (odds ratio 2.40, p = 0.008, multiple logistic regression) and with poorer visual outcome (odds ratio 1.38, p = 0.044). After keratoplasty, the visual outcome and endothelial cell density were not associated, either in penetrating or deep anterior lamellar grafts (p > 0.05). CONCLUSIONS: In keratoplasties performed for keratoconus, visual outcome cannot be predicted reliably by post-operative endothelial cell density but post-operative events can lead to poorer visual outcomes in both types of grafts.
    Clinical and Experimental Optometry 01/2013; · 0.92 Impact Factor
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    ABSTRACT: We aimed to test previous predictions that limbal epithelial stem cells (LESCs) are quantitatively deficient or qualitatively defective in Pax6(+/-) mice and decline with age in wild-type (WT) mice. Consistent with previous studies, corneal epithelial stripe patterns coarsened with age in WT mosaics. Mosaic patterns were also coarser in Pax6(+/-) mosaics than WT at 15 weeks but not at 3 weeks, which excludes a developmental explanation and strengthens the prediction that Pax6(+/-) mice have a LESC-deficiency. To investigate how Pax6 genotype and age affected corneal homeostasis, we compared corneal epithelial cell turnover and label-retaining cells (LRCs; putative LESCs) in Pax6(+/-) and WT mice at 15 and 30 weeks. Limbal BrdU-LRC numbers were not reduced in the older WT mice, so this analysis failed to support the predicted age-related decline in slow-cycling LESC numbers in WT corneas. Similarly, limbal BrdU-LRC numbers were not reduced in Pax6(+/-) heterozygotes but BrdU-LRCs were also present in Pax6(+/-) corneas. It seems likely that Pax6(+/-) LRCs are not exclusively stem cells and some may be terminally differentiated CD31-positive blood vessel cells, which invade the Pax6(+/-) cornea. It was not, therefore, possible to use this approach to test the prediction that Pax6(+/-) corneas had fewer LESCs than WT. However, short-term BrdU labelling showed that basal to suprabasal movement (leading to cell loss) occurred more rapidly in Pax6(+/-) than WT mice. This implies that epithelial cell loss is higher in Pax6(+/-) mice. If increased corneal epithelial cell loss exceeds the cell production capacity it could cause corneal homeostasis to become unstable, resulting in progressive corneal deterioration. Although it remains unclear whether Pax6(+/-) mice have LESC-deficiency, we suggest that features of corneal deterioration, that are often taken as evidence of LESC-deficiency, might occur in the absence of stem cell deficiency if corneal homeostasis is destabilised by excessive cell loss.
    PLoS ONE 01/2013; 8(8):e71117. · 3.53 Impact Factor
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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: BACKGROUND/AIMS: To characterise histopathological changes in corneal buttons associated with deep anterior lamellar keratoplasty (DALK). METHODS: This was a retrospective, clinical laboratory study. All recipient corneal buttons that underwent DALK in the West of Scotland and were submitted to the regional Ocular Pathology Laboratory (Glasgow, UK) between 2001 and 2010 were examined. Cases affected by artefacts secondary to DALK were highlighted. Keratoconus cases that underwent DALK were compared to those that underwent penetrating keratoplasty (PK). RESULTS: 225 DALK corneal buttons were examined. Of these, 61.8% were affected by artefacts or problems related to DALK. Overall, 58.2% of the affected buttons were affected by corneal emphysema related to intrastromal air injection (the 'big bubble' technique), 5.3% by epithelial oedema related to the hydrodelamination procedure, which mimicked bullous keratopathy secondary to endothelial cell deficiency, and 0.9% were lost specimens. We were not able to identify any conus, which is a characteristic histopathological feature of keratoconus, in 10 (7.4%) of the DALK-keratoconus cases as opposed to two (1.6%) of the PK-keratoconus cases (p=0.036). CONCLUSIONS: DALK poses new challenges for histopathological examination of corneal buttons. Awareness of DALK-related histopathological characteristics should be raised among ocular pathologists and ophthalmologists in view of the increasing popularity of this technique.
    The British journal of ophthalmology 10/2012; · 2.92 Impact Factor
  • Eye (London, England) 08/2012; · 1.97 Impact Factor
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    ABSTRACT: To report long term visual outcomes, complications and graft survival of patients undergoing deep anterior lamellar keratoplasty (DALK) to treat corneal scarring secondary to herpes simplex virus (HSV) keratitis. Retrospective, non-comparative case series. 18 patients who underwent DALK for HSV keratitis related corneal scarring between January 2004 and February 2007 were included. DALK was performed by Anwar's big bubble technique. Data collected for analysis included preoperative characteristics, intraoperative complications and postoperative acuity, complications and subsequent operations. Mean best corrected distance visual acuity (LogMAR) improved from 1.51±0.90 preoperatively to 0.82±0.85 at the last follow-up (p=0.05). 27% of patients with more than 4 years follow-up had a best corrected distance visual acuity of 6/12 or better and 64% were 6/24 or better. Six patients (33%) experienced a recurrence of HSV keratitis and 9 (50%) experienced an episode of graft rejection. There were five cases (28%) of graft failure, four of whom had had a previous episode of graft rejection. Logistic regression did not find an association with graft rejection, HSV recurrence, any other observed postoperative host corneal vascularisation and any postoperative complication. The majority of patients underwent a second operation with 50% requiring cataract surgery. DALK for the treatment of HSV related corneal scarring is associated with a high percentage of postoperative complications. DALK in this context is also associated with a large percentage of secondary operations. Patients should be aware of this when giving informed consent for DALK to treat HSV related corneal scars.
    The British journal of ophthalmology 07/2012; 96(9):1200-3. · 2.92 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: Long-term preservation of corneal limbal epithelium may decrease its quality and change the molecular signature of the limbal epithelial stem cells. In this study we have investigated the molecular profile of isolated corneal epithelial cells that have been in storage for an extended time. Isolated cells were characterised by the expression profile of different cytokeratins and markers of squamous metaplasia (vimentin and α‑actin). Furthermore, we examined global markers of adult stem cells including p63α and ABCG2 but also LGR5 as a novel stem cell marker. Immunocytochemical staining and PCR analysis of p63α, ABCG2 and LGR5 revealed the existence of side-population cells with a stem-cell phenotype and maintenance of corneal limbal stem cell properties. LGR5 expression can be related to cellular stemness and can be considered as a new phenotypic marker of residual human corneal limbal stem cells. However, the existence of CK10 together with co-expressed α-actin and vimentin suggests that the corneas investigated were under oxidative stress and showed evidence of squamous metaplasia.
    International Journal of Molecular Medicine 05/2012; 29(5):871-6. · 1.96 Impact Factor
  • Archives of ophthalmology 04/2012; 130(4):522-3. · 3.86 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

Publication Stats

531 Citations
201.10 Total Impact Points

Institutions

  • 2011–2013
    • Glasgow Caledonian University
      • Division of Vision Sciences
      Glasgow, SCT, United Kingdom
  • 2002–2013
    • The University of Edinburgh
      • Centre for Integrative Physiology
      Edinburgh, SCT, United Kingdom
  • 2011–2012
    • University of Glasgow
      • School of Mathematics and Statistics
      Glasgow, Scotland, United Kingdom
  • 2010
    • East Coast Community Healthcare CIC
      Beccles, England, United Kingdom