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Fulltext Comparison between point-based and ring-based technologies in Keratometric measurement among Post Myopic Laser Refractive surgery patients

Md Muziman Syah, Khairidzan Mohd Kamal, Mahfuzah Mokhtar, Aminul Hakim Sofian Sauri

International Medical Journal Malaysia, 2017;16(11):17-17.
MyJurnal

Corneal power or keratometric value represents two-third of total
refractive power of the eye. It is an important parameter in intraocular lens calculation.
Purpose of the study was to evaluate repeatability and agreement of keratometric
measurements obtained from a six points-based keratometry device; IOLMaster 500 (Carl
Zeiss Meditec AG, Jena, Germany) and two Placido disc-based keratometry devices;
Atlas Topographer 995 and 9000 models (Carl Zeiss Meditec AG, Jena, Germany). (Copied from article).

Matched MeSH terms: Cornea
Effectiveness of topical insulin for the treatment of surface corneal pathologies

Castro Mora MP, Palacio Varona J, Perez Riaño B, Laverde Cubides C, Rey-Rodriguez DV

Arch Soc Esp Oftalmol (Engl Ed), 2023 Apr;98(4):220-232.
PMID: 36871851 DOI: 10.1016/j.oftale.2023.03.007

The Purpose is to identify, through a systematic literature review, the current evidence regarding the effectiveness of topical insulin treatment in ocular surface pathologies. A literature search was implemented in Medline (Pubmed), Embase and Web Of Science medical indexing databases by using keywords such as "insulin" AND "cornea" OR "corneal" OR "dry eye" in published papers in English or Spanish within the last eleven years (2011-2022). Nine papers were identified with 180 participants from the United States, Spain, Ireland, Canada, Portugal and Malaysia, with persistent refractory epithelial defects and secondary to vitrectomy, whose extension of the lesion was from 3,75mm2 to 65.47mm2. The preparation was dissolved with artificial tears and the insulin concentration ranged from 1 IU/ml to 100 IU/ml. In all cases, the resolution of the clinical picture was complete with a healing time from 2.5 days to 60.9 days, the latter being a secondary case to a difficult-to-control caustic burn. Topical insulin has been effective for the treatment of persistent epithelial defects. The intermediate action and low concentrations showed a shorter resolution time in neurotrophic ulcers and induced during vitreoretinal surgery.

Matched MeSH terms: Cornea*
Applications of photodynamic therapy in keratitis

Anwar A, Khan NA, Alharbi AM, Alhazmi A, Siddiqui R

Int Ophthalmol, 2024 Mar 15;44(1):140.
PMID: 38491335 DOI: 10.1007/s10792-024-03062-4

Keratitis is corneal inflammatory disease which may be caused by several reason such as an injury, allergy, as well as a microbial infection. Besides these, overexposure to ultraviolet light and unhygienic practice of contact lenses are also associated with keratitis. Based on the cause of keratitis, different lines of treatments are recommended. Photodynamic therapy is a promising approach that utilizes light activated compounds to instigate either killing or healing mechanism to treat various diseases including both communicable and non-communicable diseases. This review focuses on clinically-important patent applications and the recent literature for the use of photodynamic therapy against keratitis.

Matched MeSH terms: Cornea
Corneal Epithelial Development and the Role of Induced Pluripotent Stem Cells for Regeneration

Selvarajah K, Tan JJ, Shaharuddin B

Curr Stem Cell Res Ther, 2024;19(3):292-306.
PMID: 36915985 DOI: 10.2174/1574888X18666230313094121

Severe corneal disorders due to infective aetiologies, trauma, chemical injuries, and chronic cicatricial inflammations, are among vision-threatening pathologies leading to permanent corneal scarring. The whole cornea or lamellar corneal transplantation is often used as a last resort to restore vision. However, limited autologous tissue sources and potential adverse post-allotransplantation sequalae urge the need for more robust and strategic alternatives. Contemporary management using cultivated corneal epithelial transplantation has paved the way for utilizing stem cells as a regenerative potential. Humaninduced pluripotent stem cells (hiPSCs) can generate ectodermal progenitors and potentially be used for ocular surface regeneration. This review summarizes the process of corneal morphogenesis and the signaling pathways underlying the development of corneal epithelium, which is key to translating the maturation and differentiation process of hiPSCs in vitro. The current state of knowledge and methodology for driving efficient corneal epithelial cell differentiation from pluripotent stem cells are highlighted.

Matched MeSH terms: Cornea/pathology
Liposomes in topical ophthalmic drug delivery: an update

Agarwal R, Iezhitsa I, Agarwal P, Abdul Nasir NA, Razali N, Alyautdin R, et al.

Drug Deliv, 2016 May;23(4):1075-91.
PMID: 25116511 DOI: 10.3109/10717544.2014.943336

Topical route of administration is the most commonly used method for the treatment of ophthalmic diseases. However, presence of several layers of permeation barriers starting from the tear film till the inner layers of cornea make it difficult to achieve the therapeutic concentrations in the target tissue within the eye. In order to circumvent these barriers and to provide sustained and targeted drug delivery, tremendous advances have been made in developing efficient and safe drug delivery systems. Liposomes due to their unique structure prove to be extremely beneficial drug carriers as they can entrap both the hydrophilic and hydrophobic drugs. The conventional liposomes had several drawbacks particularly their tendency to aggregate, the instability and leakage of entrapped drug and susceptibility to phagocytosis. Due to this reason, for a long time, liposomes as drug delivery systems did not attract much attention of researchers and clinicians. However, over recent years development of new generation liposomes has opened up new approaches for targeted and sustained drug delivery using liposomes and has rejuvenated the interest of researchers in this field. In this review we present a summary of current literature to understand the anatomical and physiological limitation in achieving adequate ocular bioavailability of topically applied drugs and utility of liposomes in overcoming these limitations. The recent developments related to new generation liposomes are discussed.

Matched MeSH terms: Cornea/drug effects; Cornea/metabolism; Cornea/physiology*; Cornea/chemistry*
Fulltext Central corneal thickness and intraocular pressure in Malay children

Heidary F, Gharebaghi R, Wan Hitam WH, Naing NN, Wan-Arfah N, Shatriah I

PLoS One, 2011;6(10):e25208.
PMID: 21998644 DOI: 10.1371/journal.pone.0025208

To determine the mean values for central corneal thickness (CCT) and intraocular pressure (IOP) and the relationship between these values, in healthy Malay children to serve as reference values in diagnosis and treatment.

Matched MeSH terms: Cornea/anatomy & histology*; Cornea/physiology
Histomorphometric profile of the corneal response to short-term reverse-geometry orthokeratology lens wear in primate corneas: a pilot study

Cheah PS, Norhani M, Bariah MA, Myint M, Lye MS, Azian AL

Cornea, 2008 May;27(4):461-70.
PMID: 18434851 DOI: 10.1097/ICO.0b013e318165642c

To investigate the histological changes in primate cornea induced by short-term overnight orthokeratology (OK).

Matched MeSH terms: Cornea/physiology*; Cornea/ultrastructure*
Corneal thickness and morphology after orthokeratology of six-month lens wear among young Malay adults

Mohidin N, Mat Yacob A, Norazman FN

Med J Malaysia, 2020 09;75(5):538-542.
PMID: 32918423

BACKGROUND: Menicon Z night orthokeratology (OK) lenses was introduced in Malaysia in 2015 and to date there is no report on its effects on the cornea. The objective of this study was to examine short term changes in corneal thickness and morphology of endothelial cells in young Malay adults after wearing Menicon Z night OK lenses.
METHODS: Corneal thickness was measured at the central and mid-peripheral locations of 20 participants aged 22.45±1.19 years using Tomey SP-3000 A-scan ultrasonography. Endothelial images of the central and peripheral locations captured using Tomey EM-3000 specular microscope were noted. Corneal thickness, endothelial cell density (ECD), coefficient of variation in cell size (CV), and hexagonality (HEX) at baseline, 24 hours, three months and six months after treatment were noted and analysed using repeated measure analysis of variance.
RESULTS: Central corneal thickness decreased significantly over a three-month period (p=0.001) and stabilised thereafter. There were no significant changes in thickness in all peripheral areas measured (p>0.05), and in ECD, CV and HEX after the six-month period (p>0.05).
CONCLUSIONS: The current study showed that significant thinning of central cornea and none at the mid-periphery. OK lens wear with Menicon Z night lenses had no effects on corneal morphology over the six month period.

Matched MeSH terms: Cornea/anatomy & histology*; Cornea/surgery*
Hypopyon cornea ulcer in Malaya; a hazard particularly of the rubber industry

McPHERSON HJ

Med J Malaya, 1954 Jun;8(4):318-29.
PMID: 13193269
Matched MeSH terms: Cornea*; Corneal Ulcer*
Fulltext Evaluation of the relationship between corneal diameter and lens diameter in children

Wong, C.L., Bastion, M.L.C., Ropilah, A.R., Jamalia, R.

Medicine & Health, 2020;15(2):66-84.
MyJurnal

Kajian ini bertujuan untuk mengkaji hubung kait antara diameter kornea dan diameter kanta di kalangan kanak-kanak. Kajian ini melibatkan sejumlah empat puluh kanak-kanak (40 mata) yang kurang daripada 4 tahun yang menjalani pemeriksaan, prosedur atau pembedahan di Hospital Kuala Lumpur dari Januari 2010 sehingga September 2011. Pemeriksaan dijalankan dengan menggunakan bius am di dewan bedah. Diameter kornea diukur dengan ‘Holladay-Godwin cornea gauge’ sementara diameter kanta diukur dengan menggunakan mesin ultrasound yang mempunyai resolusi tinggi ‘ultrasound biomicroscope (UBM)’. Purata umur populasi kajian adalah 24.7 + 12.1 bulan. Purata diameter kornea melintang adalah 11.62 + 0.50 mm, lebih besar berbanding dengan purata diameter kornea menegak yang berukuran 11.20 + 0.58 mm. Purata diameter kanta adalah 7.94 + 0.47 mm. Diameter kornea didapati mempunyai korelasi positif yang sederhana dengan diameter kanta (r=0.479, p=0.002). Terdapat hubung kait yang kukuh di antara diameter kanta dengan umur pesakit (r=0.718, p

Matched MeSH terms: Cornea
Fulltext New modified equation of contact lens method in determining post myopic laser refractive surgery corneal power

Md. Muziman Syah, M.M., Mutalib, H. A., Sharanjeet Kaur, M. S., Khairidzan, M. K.

International Medical Journal Malaysia, 2016;15(1):61-68.
MyJurnal

Introduction: The purpose of this study was to derive a modified equation for contact lens method (CLM) in
calculating post myopic laser refractive surgery corneal power. Methods: A total of 93 subjects who
underwent myopic laser refractive surgery at IIUM Eye Specialist Clinic were recruited. The accuracy of
postoperative corneal power using the standard CLM and newly-derived contact lens modified method
(CLMmod) were compared to the standard comparison method ; the historical method (HM). The CLMmod
equation was derived by adjusting postoperative corneal power of CLM according to amount of refractive
change. Results: The mean postoperative corneal power using standard CLM was significantly higher than
HM (mean difference: -0.24 D, p < 0.001). Fifty seven percent (n = 53 eyes) of the standard CLM results were
within ±0.50 D of HM results. The difference between postoperative corneal power using standard CLM and
HM increased significantly with the amount of refractive change (r = 0.835; p < 0.001). The mean
postoperative corneal power of CLMmod showed that there was no statistical significant difference compared
to the HM results (mean difference: 0.00 D, p= 0.964). Eighty eight percent (n = 82 eyes) of the CLMmod
results were within ±0.50 D of HM results with improvement of 31% from the standard CLM results.
Conclusion: The CLMmod equation provides more accurate calculation in determining post myopic laser
refractive surgery corneal power. In near future, this modified equation can be used as an alternative
equation to calculate postoperative corneal power when the preoperative data is unavailable.

Matched MeSH terms: Cornea
Fulltext Multifacet of Cornea Patch Graft in Anterior Segment Diseases

Chendran P, Meng Hsien Y, Wan Abdul Halim WH

Case Rep Ophthalmol Med, 2019;2019:6862487.
PMID: 31885979 DOI: 10.1155/2019/6862487

Incidence of cornea melting or perforation is commonly seen in variety of cornea conditions. It can cause debilitating vision loss and impair patient's daily activity. Several techniques have been described to surgically treat cornea perforation and melting. In this article, a series of corneal diseases treated with corneal patch graft are highlighted to relate different approach of cornea patch graft surgery. Post-operative management and complications are discussed.

Matched MeSH terms: Cornea; Corneal Ulcer; Corneal Perforation
Fulltext The Changes of Tear Status after Conventional and Wavefront-Guided IntraLASIK

Foo SK, Kaur S, Abd Manan F, Low AJ

Malays J Med Sci, 2011 Apr;18(2):32-9.
PMID: 22135584 MyJurnal

IntraLASIK is a LASIK surgery that involved IntraLase femtosecond laser for the corneal flap creating. The objective of this research was to investigate and compare the changes in tear status at 1 and 3 months after undergoing conventional IntraLASIK with Bausch & Lomb PlanoScan (PS) algorithm, Bausch & Lomb Zyoptix Tissue Saving (ZTS) algorithm, and wavefront-guided (WG) IntraLASIK with VISX CustomVue.

Matched MeSH terms: Cornea
Fulltext Iatrogenic corneal perforation in Terrien Marginal Degeneration

Mohd Razali K

Med J Malaysia, 2013 Apr;68(2):173-4.
PMID: 23629570 MyJurnal

This case report is about a rare disease with unusual presentation. Failure to recognise atypical presentation may lead to error in managing the patient and cause disastrous complications. Here we highlight a case of Terrien Marginal Degeneration in both eyes with atypical presentation; namely pseudopterygium. A 22 year old man was referred to our centre for iatrogenic right eye corneal perforation after having an atypical pterygium removed at another hospital. On arrival, his vision was 1/60 in both eyes with bilateral cornea Terrien Marginal Degeneration. His right eye anterior chamber was deep with a conjunctival flap covering the perforation site which was located from the 2.30 - 3.30 clock position nasally with no aqueous leak. However after a day his right eye anterior chamber became flat and there was fast aqueous leak from the perforation site. An emergency C shaped peripheral corneal lamellar keratoplasty was performed to seal the perforation. Post operatively his right eye improved to 6/24.

Matched MeSH terms: Cornea/surgery; Corneal Diseases/surgery; Corneal Transplantation; Corneal Perforation*
A systematic review of phacoemulsification cataract surgery in virtual reality simulators

Lam CK, Sundaraj K, Sulaiman MN

Medicina (Kaunas), 2013;49(1):1-8.
PMID: 23652710

The aim of this study was to review the capability of virtual reality simulators in the application of phacoemulsification cataract surgery training. Our review included the scientific publications on cataract surgery simulators that had been developed by different groups of researchers along with commercialized surgical training products, such as EYESI® and PhacoVision®. The review covers the simulation of the main cataract surgery procedures, i.e., corneal incision, capsulorrhexis, phacosculpting, and intraocular lens implantation in various virtual reality surgery simulators. Haptics realism and visual realism of the procedures are the main elements in imitating the actual surgical environment. The involvement of ophthalmology in research on virtual reality since the early 1990s has made a great impact on the development of surgical simulators. Most of the latest cataract surgery training systems are able to offer high fidelity in visual feedback and haptics feedback, but visual realism, such as the rotational movements of an eyeball with response to the force applied by surgical instruments, is still lacking in some of them. The assessment of the surgical tasks carried out on the simulators showed a significant difference in the performance before and after the training.

Matched MeSH terms: Cornea/surgery
Mesenchymal stromal cell-like characteristics of corneal keratocytes

Choong PF, Mok PL, Cheong SK, Then KY

Cytotherapy, 2007;9(3):252-8.
PMID: 17464757

The unique potential of mesenchymal stromal cells (MSC) has generated much research interest recently, particularly in exploring the regenerative nature of these cells. Previously, MSC were thought to be found only in the BM. However, further studies have shown that MSC can also be isolated from umbilical cord blood, adipose tissue and amniotic fluid. In this study, we explored the possibility of MSC residing in the cornea.

Matched MeSH terms: Cornea/cytology*
Patterns of tissue damage produced by repeated use of a corneal trephine: a scanning electron microscopic study

Jaais F, Dutton GN

Ophthalmic Surg, 1992 Mar;23(3):210-4.
PMID: 1574293

We studied by scanning electron microscopy the effects of the repeated use of a newly-designed, disposable, suction trephine (Microsurgical, Ltd, Bedfordshire, England) on the nature of the cut of successive corneal buttons from sheep eyes. After the trephine was used more than nine times, the cut edge became more irregular as successive buttons were produced. Also, progressively greater degrees of endothelial cells adjacent to the cut edge were lost. Although the corneal buttons initially were circular, those produced after the 20th cut became more oval. These results suggest that a disposable corneal trephine should be reused no more than nine times.

Matched MeSH terms: Cornea/ultrastructure*; Endothelium, Corneal/ultrastructure; Corneal Transplantation/instrumentation*
Fulltext Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes

Zouache MA, Eames I, Samsudin A

PLoS One, 2016;11(3):e0151490.
PMID: 26990431 DOI: 10.1371/journal.pone.0151490

In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.

Matched MeSH terms: Cornea/physiology
Fulltext Cut-it-out technique for ocular fish-hook injury

Ahmad SS, Seng CW, Ghani SA, Lee JF

J Emerg Trauma Shock, 2013 Oct;6(4):293-5.
PMID: 24339666 DOI: 10.4103/0974-2700.120384

An 11-year-old boy was involved in an injury with a fish-hook to his eye. The hook had impaled itself to the cornea and deeper structures. There was associated corneal edema and hyphema, making visualization difficult. In this case, we performed the unusual "cut-it-out" technique to remove the hook from the eye.

Matched MeSH terms: Cornea; Corneal Edema; Corneal Injuries
Fulltext Corneal thickness and curvature of one sample of young myopic population in Malaysia

Bariah Mohd-Ali, Ho, Oi Ching, NorAzizah Abd Latif

Jurnal Sains Kesihatan Malaysia, 2009;7(1):49-58.
MyJurnal

The purpose of this study is to determine the standard value of corneal thickness (CCT) and its relationship with the degree of myopia amongst one sample of myopic students in Malaysia. Eighty-four myopic subjects (168 eyes) were examined in this study. Ocular examination included subjective refraction, keratometry (Shin-Nippon, Japan) and optical pachometry (Sonogage INC). Corneal thickness was measured at five different locations i.e. central, superior, inferior, nasal and temporal of the cornea. However, only association of CCT with myopia is reported in this article. Mean age of subjects was 21.42 ± 1.47 years old (20.34 ± 1.15; 22.46 ± 0.88). Mean refractive error in spherical equivalent for the whole sample was –3.50 ± 2.10 DS. Mean corneal curvature for the all subjects was 7.74 ± 0.52 mm and mean value of CCT was 594.62 ± 66.51 mm. Significant differences (p < 0.05) were found between mean CCT of low myopes (-4.00DS and below) and higher ones (-4.25DS and above), but not with mean of keratometer readings. Poor correlations were obtained between refractive error and CCT (r = 0.125, p > 0.05) and between refractive error and corneal curvature (r = 0.24, p > 0.05). It was concluded from this study that high myopic subjects has significantly thinner CCT than lower ones. Measurement of CCT should be considered when undertaking procedures such as LASIK and orthokeratology.

Matched MeSH terms: Cornea

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