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Papers by Simon Hardman Lea

Ophthalmic and Physiological Optics, 1991

There have been various reports in the literature regarding the limits that separate acceptable f... more There have been various reports in the literature regarding the limits that separate acceptable from disturbing aniseikonia. A criterion value of 5% is often quoted but actual values in pseudophakia may vary from 2% to 10%, depending on the type and position of implant used. In the accompanying paper we have reported a method by which image size can be calculated in the pseudophakic eye. Using this method a series of patients with anterior and posterior chamber implants were analysed and the image size for both eyes of each patient determined. This was compared with the patient's subjective appreciation.

Ophthalmic and Physiological Optics, 1991

In a recent paper, Snead et al.^ calculate the position of the nodal points of the eye by paraxia... more In a recent paper, Snead et al.^ calculate the position of the nodal points of the eye by paraxial ray trace equations, for the purpose of estimating the level of aniseikonia. Ray tracing procedures are in many textbooks and in many forms, some more elegant than others. Methods for the calculations of the position of cardinal points from ray trace results should be taught in optometry schools. However, it may not be taught to any greater depth in ophthalmology courses.

The Journal of Pathology, 1994

The recent description of conjunctival lymphomas with features of lymphomas that arise in mucosa-... more The recent description of conjunctival lymphomas with features of lymphomas that arise in mucosa-associated lymphoid tissue (MALT) infers the presence of MALT in the human conjunctiva. Some authors suggest that organized MALT is found in the normal human conjunctiva, but others disagree. In order to resolve this problem, we have examined the conjunctival fornix from unselected autopsies with no prior history of conjunctival or ocular disease for the presence of organized MALT. In only 31 per cent of cases was organized lymphoid tissue found with the morphological and immunophenotypic features of MALT. This finding suggests that MALT is not found in the normal human conjunctiva but is acquired during life in a proportion of apparently asymptomatic individuals. KEY WORDS-COnjUnCtiVa, mucosa-associated lymphoid tissue (MALT), extranodal lymphoid tissue.

The Journal of Laryngology & Otology, 2007

Introduction:We performed endoscopic dacryocystorhinostomy in cases diagnosed with both anatomica... more Introduction:We performed endoscopic dacryocystorhinostomy in cases diagnosed with both anatomical and functional lacrimal obstruction, and here report results for the latter cases.Methods:Sixty-eight endoscopic dacryocystorhinostomies were performed for functional obstruction on 44 patients. The indication for surgery was epiphora in 66 patients and recurrent dacryocystitis in two. The minimum follow up was six months.Results:There was complete cure in 44 (65 per cent) patients, partial cure in nine (13 per cent) and no improvement in 15 (22 per cent). Revision surgery was performed in five of the 15 cases with no improvement, after which there was an overall complete cure in 47 patients (69 per cent), partial cure in 10 (15 per cent) and no improvement in 11 (16 per cent).Discussion:Endoscopic dacryocystorhinostomy is indicated in cases of epiphora with a diagnosis of functional lacrimal obstruction. Currently available investigations cannot reliably distinguish partial anatomical...

Acta Ophthalmologica, 2009

Abstract. The interaction between sodium fluorescein dye and hydrophilic contact lenses was asses... more Abstract. The interaction between sodium fluorescein dye and hydrophilic contact lenses was assessed quantitatively by spectrophotometry. Absorption of dye into the lens matrix was found to be proportional to the exposure time and also depends on the optical power and water content of the lens. 0.9% saline appeared preferable to oxidising agents as a rinsing solution in decontamination procedures. 3% hydrogen peroxide solution affects the nature of fluorescein such that it becomes colourless and also absorbs less incident light, whilst still being retained within the lens. The implications of our findings for practical lens decontamination and theoretical fluorescein/polymer binding are discussed.

The British orthoptic journal, 1989

A total of 465 12-year-olds were tested for their visual acuity, ocular motility, and stereopsis.... more A total of 465 12-year-olds were tested for their visual acuity, ocular motility, and stereopsis. Where any visual defect was detected, past school records were examined to discover whether the defect had previously been discovered at routine school testing. The school screening system is effective in detecting defective vision. The system for subsequent follow up is not ideal

Microbial Ecology in Health & Disease, 1988

A new method has been investigated to assess numbers of bacteria present on the normal lid and co... more A new method has been investigated to assess numbers of bacteria present on the normal lid and conjunctiva of the human eye. Counts were obtained for different colonising bacteria and limits set for normal values, which may allow for distinction between colonisation and infection. Streptococcus pneumoniae, beta-haemolytic streptococci, haemophili and coliform bacteria were not isolated from the normal eye by this methou.

Eye, 1991

Microtropia with identity is a unique condition in which amblyopes have parafoveal eccentric fixa... more Microtropia with identity is a unique condition in which amblyopes have parafoveal eccentric fixation in the amblyopic eye in either monocular or binocular viewing, plus a macular scotoma. The condition has previously been described in aniso

Eye, 1990

In a prospective study all contact lens wearers presenting to the ophthalmic casualty department ... more In a prospective study all contact lens wearers presenting to the ophthalmic casualty department of the University Hospital Nottingham within a six month period were examined to determine the number and pattern of ophthalmic problems occurring in this group. This information was then compared with prescribing information from

Eye, 1994

The results of a retrospective analysis of 49 eyes (40 patients) that underwent penetrating kerat... more The results of a retrospective analysis of 49 eyes (40 patients) that underwent penetrating keratoplasty for keratoconus are presented. All grafts had the same size trephine for both host and donor corneas. Ninety-eight per cent of eyes achieved a post-operative visual acuity of 6/12 or better; 43 % of eyes attained this level of acuity unaided, although more than half of these required spec tacles or contact lenses to reach their best corrected acuity. The average post-operathe spherical ametropia was-0.5 dioptre (SD 2.97 dioptres) and the average post operative cylinder was-3.8 dioptres (SD 2.63 dioptres). Three eyes (6%) required keratorefractive surgery to reduce astigmatism. Wound integrity was satisfactory using the same (size) trephine for both host and donor, with no patient suffering a post-operative wound leak or iris prolapse. The reduction of post-operative myopia and astigmatism is discussed. Keratoconus is one of the commonest indication� for pen etrating keratoplasty. I' The use of an ()\er�ize donor hut ton in phakic eyes was advocated to reduce the incidence of wound leakage. hecause donor corneas cut from the endothelial surface are smaller than the opening produced by the same size trephine on the epithelial surface or the host cornea.u Although success with oversize donor hut tons in terms of graft clarity is high. post-operati ve myopia and astigmatism may mar an otherwise excellent result. Recent articles have shown that the use of the same size donor and host trephines produces less post-operative myopia than is found in keratoconus patients who receive oversize donor trephines.'. � We investigated the results of 49 eyes grafted for keratoconus which

Eye, 1989

Fifty-five children with pure anisometropic amblyopia presented consecutively between 1983 and 19... more Fifty-five children with pure anisometropic amblyopia presented consecutively between 1983 and 1986. Analysis of their records was undertaken with respect to the age at presentation, the initial visual acuity after spectacle correction, and the final acuity attained after treatment. The results show that the final vision achieved does not depend on the age at presentation. The implications of these findings are dis cussed and their relations to the sensitive period for the development of amblyopia from other causes outlined.

Eye, 1990

The axial lengths of 30 pseudophakic eyes were determined by calculation using geo metric optics ... more The axial lengths of 30 pseudophakic eyes were determined by calculation using geo metric optics and by A Scan ultrasound using focused fluid filled 'soft' and solid probes. The results from the same ultrasound machine using both types of probe were ana lysed for their correlation with the calculated axial lengths. The majority of the ultrasound results were shorter than their calculated values but those obtained with the fluid filled 'soft' probe (with consequently less corneal indentation and axial length shortening) were significantly more accurate than those from the solid probe (0.02>p>0.01).

Eye, 1991

Au 82 year old patieut was lost to follow-up having been diagnosed both clinically and on CT scan... more Au 82 year old patieut was lost to follow-up having been diagnosed both clinically and on CT scan as having a right choroidal malignant melanoma. Twenty months untersuchung.

British Journal of Ophthalmology, 1990

A group of pseudophakic patients was investigated to determine whether their implants shift along... more A group of pseudophakic patients was investigated to determine whether their implants shift along an anteroposterior axis under different conditions of ciliary muscle stimulation. There was no statistically significant change in refraction after either pilocarpine or cyclopentolate administration. A change in anterior chamber depth between the position after pilocarpine and that after cyclopentolate was found. It appears that rigid posterior chamber implants do move backwards on ciliary muscle relaxation, but by a maximum 0.25 mm. This is not thought to represent a mechanical threat to ocular health. It is also not enough to account for the apparent accommodative ability of some pseudophakic patients. The possible causes for this phenomenon are discussed.

Eye, 1990

Previously published reports on the clinical features of idiopathic macular holes highlight the p... more Previously published reports on the clinical features of idiopathic macular holes highlight the predilection for post-menopausal women and implicate vitreomacular traction in the aetiology of these lesions. Relatively little attention, however, has been paid to the quality of visual loss in eyes with macular holes. Histological studies of full-thickness macular holes have shown loss of all retinal layers in the area of the hole, and this would be expected to produce a central absolute scotoma of the same diameter. The majority of patients with full-thickness holes in this series did not have an absolute scotoma large enough to be detected on the Amsler Chart or when read ing. It is suggested that following formation of a macular hole, enlargement may occur without further loss of foveal tissue and without enlargement of the absolute scotoma, due to tangential vitreous traction or contraction of an associated epiretinal membrane.

Documenta Ophthalmologica, 1990

Clinical Otolaryngology and Allied Sciences, 2001

Ophthalmic and Physiological Optics, 1991

There have been various reports in the literature regarding the limits that separate acceptable f... more There have been various reports in the literature regarding the limits that separate acceptable from disturbing aniseikonia. A criterion value of 5% is often quoted but actual values in pseudophakia may vary from 2% to 10%, depending on the type and position of implant used. In the accompanying paper we have reported a method by which image size can be calculated in the pseudophakic eye. Using this method a series of patients with anterior and posterior chamber implants were analysed and the image size for both eyes of each patient determined. This was compared with the patient's subjective appreciation.

Ophthalmic and Physiological Optics, 1991

In a recent paper, Snead et al.^ calculate the position of the nodal points of the eye by paraxia... more In a recent paper, Snead et al.^ calculate the position of the nodal points of the eye by paraxial ray trace equations, for the purpose of estimating the level of aniseikonia. Ray tracing procedures are in many textbooks and in many forms, some more elegant than others. Methods for the calculations of the position of cardinal points from ray trace results should be taught in optometry schools. However, it may not be taught to any greater depth in ophthalmology courses.

The Journal of Pathology, 1994

The recent description of conjunctival lymphomas with features of lymphomas that arise in mucosa-... more The recent description of conjunctival lymphomas with features of lymphomas that arise in mucosa-associated lymphoid tissue (MALT) infers the presence of MALT in the human conjunctiva. Some authors suggest that organized MALT is found in the normal human conjunctiva, but others disagree. In order to resolve this problem, we have examined the conjunctival fornix from unselected autopsies with no prior history of conjunctival or ocular disease for the presence of organized MALT. In only 31 per cent of cases was organized lymphoid tissue found with the morphological and immunophenotypic features of MALT. This finding suggests that MALT is not found in the normal human conjunctiva but is acquired during life in a proportion of apparently asymptomatic individuals. KEY WORDS-COnjUnCtiVa, mucosa-associated lymphoid tissue (MALT), extranodal lymphoid tissue.

The Journal of Laryngology & Otology, 2007

Introduction:We performed endoscopic dacryocystorhinostomy in cases diagnosed with both anatomica... more Introduction:We performed endoscopic dacryocystorhinostomy in cases diagnosed with both anatomical and functional lacrimal obstruction, and here report results for the latter cases.Methods:Sixty-eight endoscopic dacryocystorhinostomies were performed for functional obstruction on 44 patients. The indication for surgery was epiphora in 66 patients and recurrent dacryocystitis in two. The minimum follow up was six months.Results:There was complete cure in 44 (65 per cent) patients, partial cure in nine (13 per cent) and no improvement in 15 (22 per cent). Revision surgery was performed in five of the 15 cases with no improvement, after which there was an overall complete cure in 47 patients (69 per cent), partial cure in 10 (15 per cent) and no improvement in 11 (16 per cent).Discussion:Endoscopic dacryocystorhinostomy is indicated in cases of epiphora with a diagnosis of functional lacrimal obstruction. Currently available investigations cannot reliably distinguish partial anatomical...

Acta Ophthalmologica, 2009

Abstract. The interaction between sodium fluorescein dye and hydrophilic contact lenses was asses... more Abstract. The interaction between sodium fluorescein dye and hydrophilic contact lenses was assessed quantitatively by spectrophotometry. Absorption of dye into the lens matrix was found to be proportional to the exposure time and also depends on the optical power and water content of the lens. 0.9% saline appeared preferable to oxidising agents as a rinsing solution in decontamination procedures. 3% hydrogen peroxide solution affects the nature of fluorescein such that it becomes colourless and also absorbs less incident light, whilst still being retained within the lens. The implications of our findings for practical lens decontamination and theoretical fluorescein/polymer binding are discussed.

The British orthoptic journal, 1989

A total of 465 12-year-olds were tested for their visual acuity, ocular motility, and stereopsis.... more A total of 465 12-year-olds were tested for their visual acuity, ocular motility, and stereopsis. Where any visual defect was detected, past school records were examined to discover whether the defect had previously been discovered at routine school testing. The school screening system is effective in detecting defective vision. The system for subsequent follow up is not ideal

Microbial Ecology in Health & Disease, 1988

A new method has been investigated to assess numbers of bacteria present on the normal lid and co... more A new method has been investigated to assess numbers of bacteria present on the normal lid and conjunctiva of the human eye. Counts were obtained for different colonising bacteria and limits set for normal values, which may allow for distinction between colonisation and infection. Streptococcus pneumoniae, beta-haemolytic streptococci, haemophili and coliform bacteria were not isolated from the normal eye by this methou.

Eye, 1991

Microtropia with identity is a unique condition in which amblyopes have parafoveal eccentric fixa... more Microtropia with identity is a unique condition in which amblyopes have parafoveal eccentric fixation in the amblyopic eye in either monocular or binocular viewing, plus a macular scotoma. The condition has previously been described in aniso

Eye, 1990

In a prospective study all contact lens wearers presenting to the ophthalmic casualty department ... more In a prospective study all contact lens wearers presenting to the ophthalmic casualty department of the University Hospital Nottingham within a six month period were examined to determine the number and pattern of ophthalmic problems occurring in this group. This information was then compared with prescribing information from

Eye, 1994

The results of a retrospective analysis of 49 eyes (40 patients) that underwent penetrating kerat... more The results of a retrospective analysis of 49 eyes (40 patients) that underwent penetrating keratoplasty for keratoconus are presented. All grafts had the same size trephine for both host and donor corneas. Ninety-eight per cent of eyes achieved a post-operative visual acuity of 6/12 or better; 43 % of eyes attained this level of acuity unaided, although more than half of these required spec tacles or contact lenses to reach their best corrected acuity. The average post-operathe spherical ametropia was-0.5 dioptre (SD 2.97 dioptres) and the average post operative cylinder was-3.8 dioptres (SD 2.63 dioptres). Three eyes (6%) required keratorefractive surgery to reduce astigmatism. Wound integrity was satisfactory using the same (size) trephine for both host and donor, with no patient suffering a post-operative wound leak or iris prolapse. The reduction of post-operative myopia and astigmatism is discussed. Keratoconus is one of the commonest indication� for pen etrating keratoplasty. I' The use of an ()\er�ize donor hut ton in phakic eyes was advocated to reduce the incidence of wound leakage. hecause donor corneas cut from the endothelial surface are smaller than the opening produced by the same size trephine on the epithelial surface or the host cornea.u Although success with oversize donor hut tons in terms of graft clarity is high. post-operati ve myopia and astigmatism may mar an otherwise excellent result. Recent articles have shown that the use of the same size donor and host trephines produces less post-operative myopia than is found in keratoconus patients who receive oversize donor trephines.'. � We investigated the results of 49 eyes grafted for keratoconus which

Eye, 1989

Fifty-five children with pure anisometropic amblyopia presented consecutively between 1983 and 19... more Fifty-five children with pure anisometropic amblyopia presented consecutively between 1983 and 1986. Analysis of their records was undertaken with respect to the age at presentation, the initial visual acuity after spectacle correction, and the final acuity attained after treatment. The results show that the final vision achieved does not depend on the age at presentation. The implications of these findings are dis cussed and their relations to the sensitive period for the development of amblyopia from other causes outlined.

Eye, 1990

The axial lengths of 30 pseudophakic eyes were determined by calculation using geo metric optics ... more The axial lengths of 30 pseudophakic eyes were determined by calculation using geo metric optics and by A Scan ultrasound using focused fluid filled 'soft' and solid probes. The results from the same ultrasound machine using both types of probe were ana lysed for their correlation with the calculated axial lengths. The majority of the ultrasound results were shorter than their calculated values but those obtained with the fluid filled 'soft' probe (with consequently less corneal indentation and axial length shortening) were significantly more accurate than those from the solid probe (0.02>p>0.01).

Eye, 1991

Au 82 year old patieut was lost to follow-up having been diagnosed both clinically and on CT scan... more Au 82 year old patieut was lost to follow-up having been diagnosed both clinically and on CT scan as having a right choroidal malignant melanoma. Twenty months untersuchung.

British Journal of Ophthalmology, 1990

A group of pseudophakic patients was investigated to determine whether their implants shift along... more A group of pseudophakic patients was investigated to determine whether their implants shift along an anteroposterior axis under different conditions of ciliary muscle stimulation. There was no statistically significant change in refraction after either pilocarpine or cyclopentolate administration. A change in anterior chamber depth between the position after pilocarpine and that after cyclopentolate was found. It appears that rigid posterior chamber implants do move backwards on ciliary muscle relaxation, but by a maximum 0.25 mm. This is not thought to represent a mechanical threat to ocular health. It is also not enough to account for the apparent accommodative ability of some pseudophakic patients. The possible causes for this phenomenon are discussed.

Eye, 1990

Previously published reports on the clinical features of idiopathic macular holes highlight the p... more Previously published reports on the clinical features of idiopathic macular holes highlight the predilection for post-menopausal women and implicate vitreomacular traction in the aetiology of these lesions. Relatively little attention, however, has been paid to the quality of visual loss in eyes with macular holes. Histological studies of full-thickness macular holes have shown loss of all retinal layers in the area of the hole, and this would be expected to produce a central absolute scotoma of the same diameter. The majority of patients with full-thickness holes in this series did not have an absolute scotoma large enough to be detected on the Amsler Chart or when read ing. It is suggested that following formation of a macular hole, enlargement may occur without further loss of foveal tissue and without enlargement of the absolute scotoma, due to tangential vitreous traction or contraction of an associated epiretinal membrane.

Documenta Ophthalmologica, 1990

Clinical Otolaryngology and Allied Sciences, 2001