Neuro ophthalmology

Binocular stereopsis, or stereo vision, is the ability to derive information about how far away objects are, based solely on the relative positions of the object in the two eyes. It depends on both sensory and motor abilities. In this review, I briefly outline some of the neuronal mechanisms supporting stereo vision, and discuss how these are disrupted in strabismus. I explain, in some detail, current methods of assessing stereo vision and their pros and cons. Finally, I review the evidence supporting the clinical importance of such measurements.

Purpose To validate a table of amounts of three horizontal muscle surgery in patients with large-angle infantile esotropia (Z60 prism dioptres, PD). Methods A prospective interventional case series reporting the postoperative alignment of 51 patients (27 male, 24 female) over a 15-year period was conducted. Surgery amounts were according to a published table developed on a previous patient cohort (n ¼ 49), using bilateral medial rectus recession with graded unilateral lateral rectus resection. Kaplan-Meier lifetable survival curves were formulated for success to orthotropia (± 10 PD) after one and subsequent horizontal muscle surgeries for up to 8 years follow-up. Results The median preoperative deviation was 65 PD (range 60-80 PD) and median age at surgery was 11.8 months (range 5.1 months-3.6 years). Surgical success to orthotropia (± 10 PD) after one surgery was 100% at 2 months, 95.7% at 6 months, 91.3% at 12 months, 77.8% at 4 years, and 73.6% at 8 years. Postoperative failure requiring further horizontal surgery occurred in 17.6% (residual esotropia 4, consecutive exotropia 5). Conclusions Our second cohort has reproduced the success rate of the previous cohort (77.8% vs 77.1% at 4 years). If the published table of surgical amounts is used, three horizontal muscle surgery in large-angle infantile esotropia (Z60 PD) appears to have a good long-term success rate, and does not lead to the high rates of either residual esotropia or consecutive exotropia reported by others in the literature.

the unusual ERM appearance in our patient presumably reflects this situation. Interestingly, experimental subretinal injection of PFCLs results in phagocytosis of PFCL by RPE within 3 h of injection, 4 which may help explain the appearances of the epiretinal RPE in our patient.

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The dynamics of pupillary dilation induced by Phenylephrine 10% and Cyclopento late 1 % have been examined by flash photography. A correlation between anterior chamber depth and the pupil shape on dilation with Phenylephrine Hydrochloride J00/r, is described. It is postulated that these pupillary dilation dynamics support a s)'mpathetic abnormality as a trigger for acute primary angle closure glaucoma. The oval pupil is a common clinical sign in acute prImary angle closure glaucoma (APACG).1 APACG has been shown to occur more commonly in patients with shallO\v anterior chambers.: The acute attack is pre 1099-1117. . 1 Philips: Closed Angle Glaucoma-Significance of sectoral variations in angle depth. Br J Ophthal mol 1956. 40: 136-40. 1 Thompson HS. Zackon DH. Czarnecki JSC: Tad pole shaped pupils caused by segmental spasm of the iris dilator muscle. Am J Ophthalmol1983. 96: 467-477.

Aims To prospectively evaluate by ultrasound biomicroscopy (UBM) and gonioscopy the anterior chamber angle widening following laser peripheral iridotomy (LPI) in eyes with early chronic primary angle closure glaucoma (CACG). Methods A total of 55 eyes of 55 patients with CACG presenting with less than 1801 peripheral anterior synechiae (PAS) were enrolled in the study. Angles were assessed by gonioscopy (Shaffer's grading) and UBM, before and 4 weeks after LPI. The angle opening distance at 250 and 500 lm from the scleral spur (AOD 250 and AOD 500) was computed. Results were analysed using the Wilcoxon signed-rank test. Results In the quadrant with LPI, the mean gonioscopy grade increased significantly from 0.45 to 1.45 (Po0.001) and the mean AOD 250 and AOD 500 increased from 38.5725.9 to 83.5748.4 lm (Po0.001) and 110.2780.9 to 170.6783.4 lm (Po0.001), respectively. The angles widened significantly in the opposite quadrant on UBM (AOD 250: 48.8731.5-82.7743.9 lm, Po0.001; AOD 500:117.27 65.5-172.2781.7 lm; Po0.001), but the median gonioscopy grade remained unchanged.

Binocular stereopsis, or stereo vision, is the ability to derive information about how far away objects are, based solely on the relative positions of the object in the two eyes. It depends on both sensory and motor abilities. In this review, I briefly outline some of the neuronal mechanisms supporting stereo vision, and discuss how these are disrupted in strabismus. I explain, in some detail, current methods of assessing stereo vision and their pros and cons. Finally, I review the evidence supporting the clinical importance of such measurements.

Idiopathic full-thickness macular holes develop as a result of anteroposterior and tangential traction exerted by the posterior vitreous cortex at the fovea. Vitreoretinal relationships during the development of macular holes can be demonstrated in detail by ocular coherence tomography, facilitating an improved understanding of their pathogenesis and guiding clinical management. Surgical strategies for the repair of macular holes are designed to relieve vitreofoveal traction and to promote flattening and reapposition of the macular hole edges by intraocular gas tamponade. A period of facedown positioning postoperatively is conventionally advised. However, the evidence to support this recommendation is weak and practice varies considerably. Surgical removal of the inner limiting membrane (ILM) is advocated to ensure thorough removal of any tangential tractional components including any residual cortical vitreous. Current evidence suggests that ILM peeling can improve anatomical outcomes but the effect on visual function is less predictable; unsuccessful attempts to peel the ILM can be associated with poor visual outcome. The use of vital dyes can facilitate visualisation of the ILM and help achieve complete, atraumatic peeling. Indocyanine green dye can enable high rates of macular hole closure but has been associated with poorer visual outcomes suggesting a dosedependent toxicity. Trypan blue dye offers an alternative that may have a more favourable risk profile. An improved understanding of vitreoretinal relationships may facilitate a tailored approach to surgery in individuals with macular holes. Vitrectomy to relieve anteroposterior traction is central in the management of all full-thickness holes. The use of long-acting gases, prolonged face-down positioning, and ILM peeling may be more valuable for larger holes, longstanding holes, and those that have failed to close following conventional surgery. Vitreoretinal relationships and surgical approaches J Bainbridge et al 1302 Eye Vitreoretinal relationships and surgical approaches J Bainbridge et al Vitreoretinal relationships and surgical approaches J Bainbridge et al 1307 Eye Vitreoretinal relationships and surgical approaches J Bainbridge et al 1309 Eye

Cé cité et malvoyance bilaté rales de l'enfant de 0 à 5 ans à l'hô pital gyné co-obsté trique et pé diatrique de Yaoundé Ré sumé Nous avons mené une étude documentaire entre mars 2002 et décembre 2008, dans le but d'identifier les causes de cécité et de malvoyance bilatérales des enfants âgés de zéro à cinq ans à l'hôpital gynéco-obstétrique et pédiatrique de Yaoundé. Parmi les 55 cas enregistrés (prévalence de 2,4 %), 33 étaient des garçons et 22 des fillettes. La cécité pratique a été observée chez 69 % des enfants et la malvoyance chez 31 %. Les sites anatomiques les plus fréquemment en cause étaient le cristallin (27,3 %), le cortex visuel (25,5 %) et la rétine (14,5 %). Les atteintes étaient principalement d'origine intra utérine (41,8 %). Si le pronostic est d'emblée assez sombre pour la majorité de ces enfants, une concertation entre les autorités administratives concernées devrait permettre leur orientation précoce vers des structures de prise en charge spécialisées. Mots clés : cataracte congénitale ; cécité infantile ; malvoyance infantile.

Purpose Anisometropia of more than one dioptre during the sensitive visual period may cause amblyopia. Its management requires refractive correction, and occlusion. Compliance with treatment is critical if visual improvement is to obtained. High anisometropia, poor initial acuity and mixed strabismic/anisometropia amblyopia are predictive factors for a poor outcome. We evaluated contact lens use in the management of high anisometropic amblyopia. Methods Retrospective analysis of anisometropic amblyopia managed in a paediatric contact lens clinic (July 1996-July 2000), after standard amblyopia therapy of spectacles and occlusion therapy had been tried. Presenting age, acuity and refraction, duration of lens wear and occlusion, and final visual outcomes were noted. Results Seven children (four male, three female) presented at age 3.5-6 years (mean 4.5). Six had myopic anisometropia 6.0-18.4 dioptres (mean 10.4 dioptres) and one 6.75 dioptres hypermetropic anisometropia. The initial corrected acuities of the amblyopic eyes were 6/18 to 1/60. Five patients used contact lenses with a range from 5 months to 4 years. Final acuities were 6/12-1/60. Two myopes with 6 dioptres anisometropia improved three to four Snellen lines, one with 8.8 dioptres improved one line. Three with Ͼ10 dioptres anisometropia did not improve. The hypermetropic patient improved part of one Snellen line. Conclusions High anisometropic amblyopia is challenging to treat. In our study contact lenses improved visual acuity in myopic anisometropia of up to 9 dioptres.

Introduction Recent data suggest that there are 37 million blind people and 124 million with low vision, excluding those with uncorrected refractive errors. The main causes of global blindness are cataract, glaucoma, corneal scarring (from a variety of causes), age-related macular degeneration, and diabetic retinopathy.

METHODS:
A 32 years old female presented with Sudden painless loss of vision RE for 20 days ,Associated with pain during eye movements and headache and gives History of viral fever 15 days back. On  Ocular Examination her Best corrected visual acuity- RE -6/36; LE -6/9. Left eye pupil was having RAPD. Visual field RE revealed centrocaecal scotoma. Fundus- RE Revealed optic disc swelling with blurred margins with dilated tortuous veins and macular edema. LE- WNL. CT & MRI brain WNL.  Diagnosis of idiopathic optic neuritis made. Treatment as per Optic Neuritis was given. Visual acuity of RE improved to 6/12 after two weeks. After 20 days, she presented again with complaints of further worsening of visual acuity. Her visual acuity was 6/60 in RE. OCT of RE showed RNFL thickening & macular oedema. Her Serum CMV - IgG > 1.10 , Positive. Diagnosis of Cytomegalovirus Neuroretinitis was made. Treatment was given for CMV neuroretinitis. IV Ganciclovir induction therapy and maintenance was given.  Patient respond to the treatment. At the end of 6 month her BCVA was 6/9 in Right Eye.
CONCLUSION:
Initially patient presented  with all characteristic features of optic neuritis, but serological investigations turned out to be CMV  infection and therefore diagnosis of CMV neuroretinitis was made without any systemic manifestations of cytomegalovirus infection therefore idiopathic optic neuritis should be investigated  thoroughly.

Aim-The aim of this study was to quantify changes in refractive status over time in children with infantile esotropia and to analyse a number of clinical factors associated with infantile esotropia to determine how they may affect emmetropisation.

Abstract Purpose This study was conducted in order to investigate the effect of accommodation on the iris morphology and iridolenticular contact, in eyes with Pigment Dispersion Syndrome and Pigmentary Glaucoma, using high-resolution ultrasound.

Two infant vision screening programmes on total populations in the Cambridge Health District have been designed to identify manifest strabismus and strabismogenic and amblyogenic refractive errors at 7-9 months of age. The first, completed, programme used the isotropic photorefractor with cycloplegia together with a standard orthoptic examination. The second, current, programme uses the VRP-1 isotropic video refractor to identify infants with accommodative lags which are followed up by refraction under cycloplegia. Both programmes show good agreement between infants identified at screening and retinoscopic refractions at follow-up, showing that photo-and videorefraction (with or without cycloplegia) can be effective methods for screening for ametropia in infants and young children. In each programme 5-6% of infants showed abnormal levels of hyperopia (�3.5 D in any meridian), less than 1% showed anisometropia �1.5 D; very few infants (0.25%) showed -3 D myopia or greater. Less than 1% showed manifest strabismus. Hyperopic and anisometropic children entered a randomised controlled trial of partial refractive correc tion. All children identified at screening, alongside appropriate control groups, are extensively followed up to age 4 years. The first programme has found that children who were hyperopic in infancy were 13 times more likely to become strabismic, and 6 times more likely to show measurable acuity deficits by 4 years, compared with controls. Wearing a partial spectacle correction reduced these risk ratios to 4:1 and 2.5:1 respectively. The impaired acuity can be attributed, in part, to meridional amblyopia resulting from persisting astigmatism. Both hyperopic and myopic infants From: showed refractive changes in the direction of emme tropia between 9 months and 4 years. Wearing a partial spectacle correction did not affect this process of emmetropisation, but does provide the possibility of reducing the incidence of common pre-school vision problems. have all assisted in carrying out the screemng and follow-up. We are grateful to Dr David Vickers and members of the Department of Community Health, Cambridge Health Authority, for their support, and many general practitioners and health visitors for their co-operation. Dr Sue Atkinson (Regional Director of Public Health, South Thames), together with Oliver Braddick and 1anette Atkinson, jointly designed the first progra !ll me, Dr Sue Atkinson administered a parallel screemng programme in Bristol and is involved in cost effectiveness analysis in the second programme.

The incidence of traumatic endophthalmitis may be decreasing due to earlier wound closure and prompt initiation of antibiotics. Risk factors for endophthalmitis include retained intraocular foreign body, rural setting of injury, disruption of the crystalline lens, and a delay in primary wound closure. The microbiology in the post-traumatic setting includes a higher frequency of virulent organisms such as Bacillus species.

MORPHOLOGY Macroscopic Structure Portions of this paper were originally published in Sebag J, Wendell R, DeBustros S: Disorders of the vitreo-macular inter face. In: Margo CE, Mames RN, Hamed L, eds. Diagnostic Problems in Clinical Ophthalmology. Orlando, FL: WB Saun ders (in press) and in Sebag J: Vitreous biochemistry and struc ture. In: Albert D and Jakobiec F, eds. Principles and Practice of Ophthalmology: The Harvard System. Orlando, FL: WB Saun ders (in press).

A 6.5-year-old male neutered Trailhound was admitted for hyperacute, nonprogressive, left-sided hemipare-sis. Physical and neurologic examination revealed nonpainful, left-sided poorly ambulatory hemiparesis, decreased left-sided postural reactions and thoracic limbs hyporeflexia. Neuroanatomic localisation was consistent with a left-sided C6-T2 myelopathy. Haematology and biochemistry revealed nonspecific abnormalities. Magnetic resonance imaging of the neck revealed a focal intramedullary lesion at the level of C6-C7 vertebrae compatible with acute hydrated noncompressive nucleus pulposus extrusion or ischemic myelopa-thy. During the second day of hospitalization, the dog developed convergence-retraction nystagmus, up-gaze palsy and eyelid retraction (Collier's sign) compatible with dorsal midbrain syndrome. Magnetic resonance imaging of the brain revealed a focal lesion compatible with dorsal midbrain ischemic infarct. Further clinico-pathologic testing, thoracic and abdominal imaging were unremarkable. Ischemic encephalopathy of unknown etiology was additionally diagnosed. Physiotherapy was performed therapeutically. At 1-year follow up the dog was normal. This is an unusual report of a dog with myelopathy followed by ischemic encephalopathy with manifestation of convergence-retraction nystagmus in the absence of vestibular signs. This saccadic intrusion is a characteristic clinical manifestation of a dorsal midbrain syndrome localization. The importance of a complete differential diagnoses list formation in a dog with ischemic encephalopathy which leads to a thorough diagnostic investigation plan is highlighted. Moreover, this report contributes to the enrichment of the clinical reasoning veterinary literature on convergence-retraction nystagmus. To the authors' knowledge, this is the second case report (fourth dog) to describe convergence-retraction nystag-mus in dogs as a manifestation of dorsal midbrain syndrome.

Abstract: Eales disease is an eponym after a British ophthalmologist Henry Eales. The etiology behind Eales disease is ill-understood and stands controversial. Various systemic diseases associated with peripheral retinal revascularization and Retinal vasculitis could imitate the proliferative and inflammatory phases of Eales’ disease, respectively. We present a case of a 30 years old female patient with Eales disease and discuss the clinical features, treatment plan and its outcome in our patient.

Purpose Management decisions in intermittent distance exotropia vary and lack well-defined clinical guidelines. We undertook a systematic review in an attempt to clarify the effects of various surgical and nonsurgical treatments and to establish the significance of factors such as age with respect to outcome. The review was undertaken in collaboration with the Cochrane Eyes and Vision Group. Methods Electronic and manual searches were undertaken to identify randomised controlled trials of surgical or nonsurgical treatments for intermittent distance exotropia. We also contacted researchers active in this field for information about further published or unpublished studies. There were no language restrictions. Study abstracts identified from the searches were analysed independently by the two reviewers (SR and LG) and marked for inclusion, exclusion, or consideration. Reviewer analysis was compared and full papers for appropriate studies were requested. Results No randomised controlled trials were found that met our selection criteria. Conclusions The current literature consists mainly of retrospective reviews. These are difficult to compare and analyse due to variations in definition, intervention criteria, and outcome measures. However, there appears to be an agreement that the nonsurgical treatment is more appropriate in small-angle deviations or as a supplement to surgery. Studies supporting both early and late surgical intervention were found, so the optimal timing of surgical intervention could not be concluded. There is a need for robust clinical trials to improve the evidence base for the management of this condition.

Accumulation of lipofuscin is one of the most characteristic features of ageing observed in retinal pigment epithelial (RPE) cells. The lipofuscin found in RPE cells differs from that of other body tissues due to the fact that it is mainly derived from the chemically modified residues of incompletely digested photorecep tor outer segments. It is a heterogeneous material composed of a mixture of lipids, proteins, and different fluorescent compounds, the main fluorophore of which has recently been identified as a derivative of vitamin A. Research interest has variously focussed on the roles of age, light damage, free radicals, antioxidants, visual pigments, retinal locus, lysosomal enzymes, and pigmentation on lipofuscin formation, as well as the effects of lipofuscin on RPE cell function and causation of retinal disease. This article reviews the recent advances in knowledge of the composition, origin, and possible deleterious effects of RPE cell lipofuscin.

Congenital and infantile cataracts produce deprivation amblyopia and can thus cause lifelong visual impairment. Successful management is dependent on early diagnosis and referral for surgery when indicated. Accurate optical rehabilitation and postoperative supervision are essential.

Asteroid hyalosis (AH) is a common degenerative process in which fatty calcium globules collect within the vitreous humour. The condition rarely causes visual disturbances, and surgical removal is only rarely required. The presence of AH has been associated with systemic diseases such as diabetes; however, research in this area has been hampered by the lack of an animal model of AH. Recently, we have reported that AH occurs in galactose-fed beagles that develop the advanced stages of diabetes-like retinopathy. Comparisons of vitreous humour containing asteroid bodies (ABs) collected from these galactose-fed beagles and vitreous samples from age-matched normal beagles without ABs indicate that ABs contain calcium and phosphorous. Subtraction analysis of chloroform extracts of the vitreous samples by electrospray mass spectroscopy resulted in the identification of the quasimolecular ion of 1,2dipalmitoyl-glycero-3-phosphoethanolamine (DPPE) as the main component of ABs. Since several reports indicate that ABs are composed of lipid-calcium complexes, we have proposed that the main component of ABs in the galactose-fed dogs with AH is a quasimolecular ion of DPPE in which two molecules of DPPE are complexed through their phosphates groups with calcium. We suggest that these lipid components diffuse into the vitreous from the degenerating retinas of these dogs.

Purpose In chronic renal failure (CRF) patients the risk of per-and post-operative complications in cataract surgery is high. The most frequent complications observed in these patients and the prevalence of cataract were studied. Methods Eighty-two CRF patients who had undergone ophthalmic examination between were retrospectively analysed. Of 82 patients, 18 eyes of 14 CRF patients between 37 and 79 years of age underwent cataract extraction. Planned extracapsular cataract extraction was performed in all patients and all but one had posterior chamber intraocular lens implantation. In the post-operative period, scrapings of the corneal infiltrates were cultured and smears were examined, and the conjunctiva was swabbed and cultured also. Results Per-operative hypotony and scleral collapse occurred in 1 patient, and another had haemorrhage in the anterior chamber. Post operatively, suture infiltration was observed in 10 eyes. These lesions disappeared after topical steroid and antibiotic treatment.

Introduction: One of the autoimmune disease is Myasthenia gravis. Myasthenia gravis is an autoimmune disease characterized by a fluctuating weakness of voluntary muscles. The weakness of myasthenic patients is due to an antibodymediated autoimmune attack against acetylcholine receptor at neuromuscular junction. Normally impulses travel down the nerve and nerve endings release a substance called acetylcholine. Acetylcholine binds or attaches to receptor on the muscle and makes the muscle contract. Objective: To Diagnose the Myasthenia gravis patients prevent the autoimmune disease process with help of adjuvant therapy.

Purpose To report the effects of arteriovenous adventitial sheathotomy on anatomical and functional improvements in patients with macular oedema due to branch retinal vein occlusion (BRVO). Methods Pars plana vitrectomy and arteriovenous sheathotomy was performed on 11 patients with BRVO who had vision loss due to macular oedema. Ten patients with macular oedema due to BRVO and who have been treated with grid laser photocoagulation were included in the control group. The measurement of visual acuity with ETDRS chart was taken preoperatively and at 1, 3, 6, and 9 months follow-up in the study group and at 1, 3, 6, and 9 months after grid laser in the control group. Results The mean preoperative logMAR visual acuity was 0.8470.3 in the surgical group and 1.0670.4 in the control group. The postoperative mean logMAR visual acuity was 0.4170.2, 0.4070.2, 0.4070.3, and 0.3670.3 at 1, 3, 6, and 9 months follow-up, respectively. In the control group the postlaser mean logMAR visual acuity was 0.9270.3, 0.8770.4, 0.8570.3, and 0.8270.3 at 1, 3, 6, and 9 months follow-up, respectively. The improvements of visual acuity in both groups were statistically significant when compared to pretreatment (P ¼ 0.003 and P ¼ 0.007 at 9 months in the study and control group, respectively). Conclusion Arteriovenous sheathotomy for decompression of BRVO in patients who have vision loss due to macular oedema was safe and effective for anatomical and functional improvement and resulted in significantly better visual outcomes than a matched control group of laser-treated eyes.

Purpose To compare ocular, internal, corneal aberrations, and contrast sensitivity in patients implanted with aspheric or spherical intraocular lenses (IOLs). Methods Total, corneal, and internal aberrations were measured using ray-tracing technology in 23 eyes implanted with aspheric (Tecnis ZA9003) IOLs, and in 25 eyes implanted with spherical (AcrySof SA60AT) IOLs. Spherical aberration (SA), coma, trefoil, and RMS of higher order aberrations (HOAs) were analysed for 4.0 and 6.0 mm optical zones. Best-corrected visual acuities (BCVAs), contrast sensitivity under photopic and mesopic conditions, and modulation transfer function (MTF) were evaluated to compare visual performances. Results The mean internal SA was À0.06/ À0.35 lm in the aspheric IOL group and 0.04/ 0.17 lm in the spherical IOL group (at 4 mm/ 6 mm pupil). Total SA was near to zero in the aspheric IOL group, and was 0.11±0.034/ 0.48±0.13 lm in the spherical IOL group. The internal Z 3 À1 and total Z 3 À1 were more negative in the spherical IOL group. The internal Z 3 À3 was more negative in the aspheric IOL group. The two groups were similar in terms of other Zernike values and RMS of HOA. There were no differences in BCVA between groups. The aspheric IOL group showed better contrast sensitivity at 3-6 cpd in photopic and 1.5-6 cpd in mesopic conditions. The MTF curve was better for the aspheric IOL group at 5-10 cpd. Conclusions The aspheric IOL with a negative SA reduced total SA by compensating for positive corneal SA. These effects resulted in improved contrast sensitivity.

To determine the ability of in vitro one-dimensional and two-dimensional proton MR spectroscopy to help differentiate squamous cell carcinoma of the extracranial head and neck from normal tissues and to correlate the in vitro observations with clinical studies. METHODS: In vitro 1-D and 2-D correlated proton MR spectroscopy (11 T) was performed in tissue specimens of squamous cell carcinoma of the head and neck (n ϭ 19), in normal tissue (n ϭ 13), in metastatic cervical lymph nodes (n ϭ 3), and in a squamous cell carcinoma cell line. In vivo 1-D proton MR spectroscopy (1.5 T) was performed in patients with squamous cell carcinoma (n ϭ 7) and in healthy volunteers (n ϭ 7). The ratio of the areas under the choline (Cho) and creatine (Cr) resonances were calculated for 1-D proton MR spectra for the in vitro tissue studies and correlated with the in vivo studies. Data from in vitro 2-D correlated spectroscopy were analyzed for differences in the presence or absence of various metabolites in samples of tumor and normal tissue. Statistical analysis consisted of 2 ϫ 2 factorial repeated measures analysis of variance (ANOVA), discriminate analysis, and 2 test. RESULTS: The mean in vitro 1-D proton MR spectroscopic Cho/Cr ratio was significantly higher in tumor than in normal tissue. The difference between the mean ratios appeared to increase with increasing echo time. All in vivo tumor Cho/Cr ratios were greater than the calculated mean in vitro tumor ratio, whereas six of the seven volunteers had no detectable Cho and Cr resonances. Two-dimensional correlated MR spectroscopic data revealed that a variety of amino acids have a significantly greater likelihood of being detected in tumor than in normal tissues. CONCLUSIONS: One-dimensional and 2-D proton MR spectroscopy can help differentiate primary squamous cell carcinoma and nodal metastases containing squamous cell carcinoma from normal tissue both in vitro and in vivo. In addition, 2-D spectroscopy can help identify the presence of certain amino acids in squamous cell carcinoma that are not detected in normal tissue.