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Biomedical subjects

R A Saunders

Publications and source records attributed to R A Saunders.

At least 19 recordsLinked to original sources
PubMed2001

The amblyopia treatment study visual acuity testing protocol.

OBJECTIVE: To evaluate the reliability of a new visual acuity testing protocol for children using isolated surrounded HOTV optotypes. METHODS: After initial pilot testing and modification, the protocol was evaluated using the Baylor-Video Acuity Tester (BVAT) to present isolated surrounded HOTV optotypes. At 6 sites, the protocol was evaluated for testability in 178 children aged 2 to 7 years and for reliability in a subset of 88 children. Twenty-eight percent of the 178 children were classified as having amblyopia. RESULTS: Using the modified protocol, testability ranged from 24% in 2-year-olds to 96% in 5- to 7-year-olds. Test-retest reliability was high (r = 0.82), with 93% of retest scores within 0.1 logMAR unit of the initial test score. The 95% confidence interval for an acuity score was calculated to be the score +/-0.125 logMAR unit. For a change between 2 acuity scores, the 95% confidence interval was the difference +/-0.18 logMAR unit. CONCLUSIONS: The visual acuity protocol had a high level of testability in 3- to 7-year-olds and excellent test-retest reliability. The protocol has been incorporated into the multicenter Amblyopia Treatment Study and has wide potential application for standardizing visual acuity testing in children.

Amblyopia↗
PubMed2001

Intravitreal injection of plasminogen kringle 5, an endogenous angiogenic inhibitor, arrests retinal neovascularization in rats.

AIMS/HYPOTHESIS: Plasminogen kringle 5 is an endogenous angiogenic inhibitor. The purpose of the present study was to explore the potential application of kringle 5 in the treatment of retinal neovascularization. METHODS: Plasminogen kringle 5 was expressed in E. coli and affinity-purified. Its anti-angiogenic activity was determined in cultured primary human capillary endothelial cells. Retinal neovascularization was induced in newborn rats by exposure to hyperoxia and then normoxia. Kringle 5 was intravitreally injected into the rat model. Retinal neovascularization was visualized by fluorescein angiography on flat-mounted retina and quantified by counting preretinal vascular cells. RESULTS: Plasminogen kringle 5 inhibited primary endothelial cells but not retinal neuronal cells, suggesting cell type-specific inhibition. The oxygen-induced retinopathy rat model showed an over-expression of vascular endothelial growth factor, preretinal neovascularization and haemorrhage. Intravitreal injection of kringle 5 before the development of neovascularization resulted in fewer neovascular tufts and pre-retinal vascular cells than in control rats with PBS injection (p < 0.01). Moreover, injection of kringle 5 after the development of neovascularization inhibited the increase in the preretinal vascular cells (p < 0.05). These results suggest that kringle 5 both prevents the development and arrests the progression of retinal neovascularization. The injection of kringle 5 did not result in any detectable inflammatory response in the retina or histological toxicity to retina neurons and pre-existing vessels. CONCLUSION/INTERPRETATION: These observations suggest that intravitreal delivery of angiogenic inhibitors could have therapeutic benefits in neovascular diseases of the retina.

Angiogenesis Inhibitors↗
PubMed2001

Duane retraction syndrome.

Duane retraction syndrome (DRS) consists of deficient horizontal eye movements, eyelid retraction, palpebral fissure narrowing, and abnormal vertical eye movements. Most cases are sporadic and unilateral (usually left side) with a slight female predominance. Several associated ocular and systemic conditions have been described in DRS patients. In most cases, the abducens nucleus and nerve are absent or hypoplastic, and the lateral rectus muscle is innervated by a branch of the oculomotor nerve. However, there may be contributing mechanical abnormalities. Type I DRS (primary gaze position esotropia with limitation of abduction) comprises the majority of cases. Approximately 50% of type I DRS patients are orthophoric in primary gaze. Esotropia is the most common type of strabismus encountered, and characteristic up shoots and down shoots occur in adduction. Surgical intervention has gradually become more popular in order to improve the primary gaze alignment and mitigate some of the associated abnormalities in ocular motility. However, patients are rarely rendered clinically normal, and limited expectations are appropriate.

Adolescent↗
PubMed2000

Disinfection of eyelid specula with chlorhexidine gluconate (Hibiclens) after examinations for retinopathy of prematurity.

BACKGROUND: The preferred method of cleaning eyelid specula between examinations for retinopathy of prematurity is unknown. A previous study showed that disinfection with 70% isopropyl alcohol swabs fails to eliminate viruses and bacteria from the specula. OBJECTIVE: To determine if alternative sterilization procedures would allow multiple use of a single speculum without risking nosocomial infection. METHODS: In phase 1, 40 autoclave-sterilized eyelid specula were randomized into either "cleaned" or "patient control" groups after being used for routine retinopathy of prematurity examinations performed in the outpatient setting. Specula in the cleaned group were cleaned with chlorhexidine gluconate (Hibiclens). Specula in the patient control group were not cleaned after use. All study specula were placed into enriched culture media from which bacterial and fungal cultures were obtained. In phase 2, 20 autoclave-sterilized eyelid specula were inoculated with a clinically relevant dilution of adenovirus serovar 5 or herpes simplex type 2. Specula were randomized into either a cleaned or a control group, and cell cultures and immunofluorescence assays were used to document and confirm, respectively, viral growth. RESULTS: In phase 1, all 20 cultures from the patient control group grew bacteria compared with 0 (0%) of 20 cultures from the cleaned group and 0 (0%) of 5 from the cleaned control group. No fungi were isolated from any group. In phase 2, all 10 cultures from specula inoculated with adenovirus serovar 5 grew virus. None of the cultures from the 5 cleaned specula inoculated with herpes simplex type 2 grew virus. In contrast, all 5 cultures in the control group were positive for growth of herpes simplex type 2. CONCLUSIONS: Autoclave sterilization is the ideal method of sterilization of eyelid specula between neonate examinations. When an alternative disinfection technique is required, washing the speculum with chlorhexidine gluconate and tap water is preferred over wiping with a 70% isopropyl alcohol swab. Arch Ophthalmol. 2000;118:786-789

Adenoviruses, Human↗
PubMed2000

Outcomes from surgical treatment for dissociated horizontal deviation.

BACKGROUND AND PURPOSE: Long-term treatment results and recommendations for dissociated horizontal deviation (DHD) are sparse in the literature. We report the results of surgery for DHD with a mean of 48 months postsurgical follow-up. PATIENTS AND METHODS: Records were reviewed for 33 consecutive patients who underwent surgery to correct DHD between 1991 and 1997. Patient data were recorded, including age at time of DHD operation, initial diagnosis, history of prior surgery, number of operations related to DHD, amount of preoperative DHD for each operation, presence of concomitant esotropia or exotropia (XT), presence of amblyopia, type of operation performed, time interval between operations, and final alignment. RESULTS: Twenty-five patients (78%) underwent a single operation for DHD. Seven patients (22%) underwent 2 operations, and 2 of those 7 patients (6% of the total) underwent 3 operations to control DHD and/or horizontal strabismus accompanying the DHD. Most patients (75%) had a prior history of congenital esotropia, which had been previously corrected with bilateral medial rectus muscle recession. Patients with an XT and DHD required bilateral surgery more frequently to control their deviation. CONCLUSION: When DHD is prominent and manifests frequently, a surgical plan specific to the horizontal drift of the eyes is needed. Unilateral lateral rectus muscle recession appears to be adequate to control manifest DHD over time in most patients. Bilateral surgery will be needed occasionally for bilateral DHD when alternate fixation is present and frequently when XT and DHD coexist.

Amblyopia↗
PubMed2000

Two-muscle surgery for congenital esotropia: rate of reoperation in patients with small versus large angles of deviation.

INTRODUCTION: Standard surgical treatment of congenital esotropia (CET) in patients with preoperative angles of deviation measuring </=50 PD is well defined. However, there is controversy over the management of larger angles of esotropia. Some surgeons prefer to operate on 3 or 4 horizontal rectus muscles, while others prefer to perform large recessions of the medial rectus muscles alone. The purpose of this study was to compare the rate of reoperation after bilateral medial rectus muscle recession of smaller angle (< or =50 PD) CET with the rate of reoperation after surgery for larger angle (>50 PD) CET. METHODS: Medical records of 102 patients who underwent bilateral medial rectus muscle recessions between January 1991 and December 1997 were reviewed. Patients were excluded if neurologic abnormalities or developmental delays were documented before the operation, if major structural abnormalities of the eye were present, or if less than 1-month follow-up after surgery was documented. The remaining 56 patients were assigned to either the larger angle (>50 PD) or smaller angle (< or =50 PD) group, based on the magnitude of their preoperative esotropia. Rates of reoperation for residual CET, for consecutive exotropia or dissociated horizontal deviation, or for dissociated vertical deviation with or without oblique muscle dysfunction were determined for each group. RESULTS: Forty of 56 patients (71%) were assigned to the smaller angle group and 16 of 56 patients (29%) to the larger angle group. In the larger angle group, 4 patients (25%) underwent surgery for residual esotropia. In the smaller angle group, 8 patients (19%) underwent surgery for residual esotropia, 8 (19%) underwent surgery for consecutive exotropia or dissociated horizontal deviation, and 8 (19%) underwent surgery for dissociated vertical deviation or oblique muscle dysfunction. CONCLUSION: The success rate for ocular realignment in patients with CET by using bilateral medial rectus muscle recession did not appear to diminish when applied to deviations greater than 50 PD as compared with smaller angle deviations. Surgery on 3 or 4 horizontal rectus muscles may be unnecessary in the treatment of patients with very large angles of CET.

Esotropia↗
PubMed2000

Non-ophthalmologist screening for retinopathy of prematurity.

AIM: To determine if a non-ophthalmologist can accurately screen for retinopathy of prematurity (ROP) by evaluating the posterior pole blood vessels of the retina. ROP is a common ocular disorder of premature infants and may require multiple screening examinations by an ophthalmologist to allow for timely intervention. Since there is a strong correlation between posterior pole vascular abnormalities and vision threatening ROP, screening examinations performed by non-ophthalmologist may yield useful clinical information in high risk infants. METHODS: Infants born at the Medical University of South Carolina who met screening criteria (n = 142) were examined by a single non-ophthalmologist using a direct ophthalmoscope to evaluate the posterior pole blood vessels for abnormalities of the venules and/or arterioles. To determine the accuracy of the non-ophthalmologist's clinical observations, infants were also examined by an ophthalmologist, using an indirect ophthalmoscope, who graded the posterior pole vessels as normal, dilated venules, or dilated and tortuous venules and arterioles (including "plus disease"). RESULTS: There was significant correlation (p <0.001) between the non-ophthalmologist's and ophthalmologist's diagnoses of posterior pole vascular abnormalities. 47 infants had normal posterior pole blood vessels by the non-ophthalmologist examination. Of these, 31 (66%) were considered to have normal vessels and 16 (34%) to have dilated venules by the ophthalmologist. The non-ophthalmologist correctly identified abnormal posterior pole vessels in all 21 infants diagnosed with abnormal arterioles and venules by the ophthalmologist. No infants with clinically important ROP ("prethreshold" or worse) would have failed detection by this screening method. CONCLUSION: Using a direct ophthalmoscope, a non-ophthalmologist can screen premature infants at risk for ROP by evaluating the posterior pole blood vessels of the retina. While not necessarily recommended for routine clinical practice, this technique may nevertheless be of value to those situations where ophthalmological consultation is unavailable or difficult to obtain.

Humans↗
PubMed2000

Surgical management of strabismus after rupture of the inferior rectus muscle.

BACKGROUND: Rupture of an inferior rectus muscle is an uncommon problem. The resulting absence of infraduction and large hypertropia that result when the muscle cannot be repaired are challenging to manage surgically. METHODS: We treated 2 patients who had traumatic rupture of the inferior rectus muscle. Both patients underwent an inferior transposition of the inferior halves of the medial and lateral rectus muscles without disinsertion (modified Jensen transposition procedure). RESULTS: Both patients had a persistent small overcorrection in the primary gaze position. One patient was treated with a second strabismus surgery consisting of a recession of the contralateral superior rectus muscle; the other was treated with prism glasses. Both achieved restoration of depression to approximately 40 degrees and single binocular vision in the primary position at distance, near, and in the reading position. CONCLUSION: This modified Jensen transposition procedure of the horizontal rectus muscles appears to be highly effective in the treatment of the hypertropia and infraduction deficit produced by rupture of the inferior rectus muscle. It also appears to be suitable for use in situations when other rectus muscles are absent or unavailable for surgical manipulation.

Aged↗
PubMed1999

Color doppler imaging of the central retinal artery in premature infants undergoing examination for retinopathy of prematurity.

PURPOSE: Recent attempts have been made to quantify blood flow velocity in the central retinal artery (CRA) of adults using color Doppler imaging (CDI). Although retinal vascular abnormalities are the hallmark of severe retinopathy of prematurity (ROP), normal values have not been established for CRA blood flow velocity in premature infants. METHODS: CDI of the CRA was successfully performed on 43 eyes in 22 infants (postconceptional ages 32 to 39 weeks) before the infants underwent examination for ROP. Peak systolic velocity (PSV) and end diastolic velocity were recorded from at least 1 eye of each patient. Pourcelot's resistive index was then calculated for each eye studied. RESULTS: Mean PSV for patients with no ROP (n = 6) was 7.2 +/- 1.5 cm/s, whereas those with any degree of ROP excluding plus disease (n = 9) had a mean PSV of 8.9 +/- 1.8 cm/s. Of the patients with ROP and plus disease (n = 7), the mean PSV was 7.0 +/- 1.6 cm/s. There were no statistically significant differences among these 3 groups (P= .08). CONCLUSIONS: CDI can be successfully performed on preterm infants and yields values lower than those previously reported in healthy adult subjects. PSV in the CRA may be higher in subjects with ROP in the absence of plus disease; however, further study is needed to determine whether these differences are significant.

Blood Flow Velocity↗
PubMed1998

Timing of initial screening examinations for retinopathy of prematurity.

OBJECTIVE: To test a screening protocol for retinopathy of prematurity (ROP) that uses the dual criteria of postconceptional age and chronological age, rather than a single parameter, to determine precisely when to begin eye examinations. METHODS: We retrospectively reviewed medical records of 179 infants (326 eyes) who had undergone laser treatment for threshold ROP. We entered their chronological and postconceptional ages at treatment into a database and evaluated various screening parameters to determine the combination of criteria that would allow us to safely postpone the initial eye examinations. RESULTS: Screening infants at 7 weeks of chronological age or 34 weeks of postconceptional age (whichever comes first), but not before 5 weeks of chronological age, seems to reliably detect the onset of threshold ROP while reducing the number of unnecessary early examinations. CONCLUSION: Simultaneously applied dual criteria of chronological age and postconceptional age may be a superior method of determining when to initiate ROP examinations and is preferable to using either chronological age or postconceptional age alone.

Age of Onset↗
PubMed1998

Outcomes and ocular growth rates after intraocular lens implantation in the first 2 years of life.

PURPOSE: To evaluate the outcomes and ocular growth after intraocular lens (IOL) implantation in the first 2 years of life. SETTING: University-affiliated eye institute. METHODS: The medical records of consecutive children under 24 months of age who had cataract extraction with IOL implantation were reviewed. Change in axial length over time, postoperative complications, need for additional surgery, predicted versus actual postoperative refraction, and visual outcomes were recorded. Complication rates were compared with those in a similar group of age-matched patients who were left aphakic at the time of surgery. RESULTS: Twenty-two eyes of 17 patients aged 12 days to 22 months had IOL implantation. Length of follow-up ranged from 2 to 36 months (mean 14 months). Visual acuity measurement, limited to fixation-preference testing in most patients, revealed amblyopia in the operated eye in the majority of cases. Postoperative refractive error, predicted using the Holladay formula, showed a mean error in prediction of 1.5 diopters (D) (range -1.8 to 4.1 D). Serial axial lengths in 11 patients with a mean follow-up of 20 months showed no significant difference in growth in the fellow versus the operated eye. There was no significant difference in complication rates between pseudophakic patients and the age-matched aphakic group. However, in 14 of 32 aphakic eyes (44%), a notation in the chart indicated that the patient had stopped wearing glasses or contact lenses for at least 2 months. CONCLUSION: Intraocular lens implantation appeared to be a safe and effective alternative to contact lens or spectacle correction of aphakia in children younger than 2 years of age. It may aid amblyopia treatment by eliminating periods of uncorrected aphakia.

Aphakia, Postcataract↗
PubMed1998

Acquired cataracts after argon laser photocoagulation for retinopathy of prematurity.

PURPOSE: Our purpose was to determine the incidence of cataract after argon laser photocoagulation of the retina in infants with retinopathy of prematurity (ROP). METHODS: We reviewed medical records of 189 consecutive infants undergoing argon laser photocoagulation for acute ROP between 1993 and 1996. Birth weight, estimated gestational age at birth, chronologic and postconceptional ages at the time of treatment, ROP outcome, and the postoperative occurrence of cataract were recorded. RESULTS: A total of 374 eyes in 189 infants were treated for threshold ROP. Mean birth weight was 916 gm (range 480 to 2500 gm), mean postconception age at birth was 26.4 weeks (range 23.5 to 34 weeks), and mean postconception age at surgery was 36.2 weeks (range 33 to 47 weeks). A favorable anatomic outcome occurred in 90% of eyes. However, severe macular traction, macular fold, or retinal detachment developed in 10% of eyes. A total of four eyes (1%) had cataracts. Laser-induced cataracts were diagnosed in only two eyes. A third eye had a posterior subcapsular cataract that may or may not have resulted from the laser treatment. In a fourth patient a unilateral punctate opacity judged to be visually insignificant was noted at surgery but it was not progressive. All patients who had cataracts had a persistent tunica vasculosa lentis; however, there was no statistically significant difference in the incidence of cataract formation in eyes with persistent tunica vasculosa lentis compared with eyes without it (p = 0.057). CONCLUSION: Argon laser photocoagulation remains an effective alternative to transscleral cryotherapy in the treatment of threshold ROP. The incidence of cataract formation is approximately 1% and may be more likely to occur when persistent hyaloidal vessels are present on the lens.

Birth Weight↗
PubMed1997

Racial variation in retinopathy of prematurity. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

OBJECTIVES: To determine and compare the incidence of severe, vision-threatening retinopathy of prematurity (ROP) in black and white low-birth-weight infants. DESIGN: Prospective cohort study. SETTING: Seventy neonatal intensive care units in 23 US participating centers in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity. PATIENTS: A total of 4099 premature infants weighing less than 1251 g at birth were enrolled to evaluate the natural history of ROP. This 'Natural History' cohort included 2158 white infants and 1584 black infants who were followed up prospectively according to a Natural History protocol. MAIN OUTCOME MEASURES: Incidence and severity of acute ROP. RESULTS: While ROP occurred with similar frequency in all racial subgroups, severe ROP was less common in black infants. One hundred sixty (7.4%) of 2158 white infants reached threshold ROP (defined as at least 5 contiguous or 8 cumulative clock-hours of stage 3 retinopathy in zone 1 or zone 2 in the presence of "plus disease" [dilation and tortuosity of the posterior pole blood vessels]), but only 51 (3.2%) of 1584 black infants progressed to threshold ROP. Using multiple logistic regression analysis, race emerged as a highly significant factor (P < .001) in the development of threshold disease, even when birth weight, gestational age status at delivery, sex, multiple births, and transport status were considered. CONCLUSIONS: Severe, vision-threatening ROP occurs with greater frequency in low-birth-weight white infants than in low-birth-weight black infants who are seemingly at equivalent risk. The reason for this disparity is unknown. We speculate that differences in retinal pigmentation may confer relative protection against free radical-mediated phototoxic injury in black infants.

Birth Weight↗
PubMed1997

Combined bilateral superior rectus muscle recession and inferior oblique muscle weakening for dissociated vertical deviation.

PURPOSE: Dissociated vertical deviation (DVD) is a common disorder that is often difficult to treat satisfactorily with extraocular muscle surgery. Weakening both elevators in a single eye is uncommonly performed because of possible severe upgaze deficiency or chin-up head posture postoperatively. METHODS: A retrospective review of medical records was performed that yielded 14 patients who had undergone bilateral superior rectus muscle recessions (mean 8.1 mm, range 5-10 mm) and bilateral inferior oblique muscle recession, myectomy, or anterior transposition in the treatment of DVD. Three additional patients with asymmetric inferior oblique muscle overaction or true hypertropia in primary gaze position were identified who had bilateral superior rectus muscle recessions combined with unilateral inferior oblique muscle weakening. RESULTS: Mild-to-moderate elevation deficiencies were common postoperatively but never exceeded -2 up-gaze limitation (scale 0 to -4) except in the immediate postoperative period and were not associated with persistent chin-up head posturing. Cosmetically objectionable upper eyelid retraction occurred in one patient after re-recession of a superior rectus muscle but before inferior oblique muscle surgery. Only three patients undergoing four vertical muscle surgeries had residual DVD >10 PD in primary gaze position, and none exhibited manifest dissociated strabismus warranting further treatment. CONCLUSION: Bilateral superior rectus muscle recession of up to 10 mm combined with inferior oblique muscle weakening appears to be a safe surgical approach in the management of patients with large angle or recurrent DVD. Our data further suggest that simultaneous four vertical muscle surgery may be preferred in some patients to weakening the superior rectus or inferior oblique muscles alone.

Depth Perception↗
PubMed1995

Grating visual acuity in eyes with retinal residua of retinopathy of prematurity. The Cryotherapy for Retinopathy of Prematurity Cooperative Group.

OBJECTIVES: To compare grating visual acuity of eyes with varying severity of retinal residua of retinopathy of prematurity to grating visual acuity of eyes that did not have acute-phase retinopathy of prematurity, showed no ocular abnormalities on follow-up, and were from patients who passed neurodevelopmental screening questions. DESIGN: Monocular grating visual acuity was measured by means of the Teller acuity card procedure when children reached 1, 2, 3 1/2, and 4 1/2 years of age. PATIENTS: A total of 1398 children with birth weights less than 1251 g whose acute-phase retinopathy of prematurity was documented as part of the Multicenter Cryotherapy for Retinopathy of Prematurity Study and who participated in follow-up visual acuity testing. RESULTS: Eyes with no or mild residua of retinopathy of prematurity showed a mean visual acuity similar to that of the comparison group. Eyes in a subgroup with abnormally straightened temporal retinal vessels showed a mean visual acuity approximately 1 octave below that of the comparison group. Mean visual acuity scores from eyes with macular heterotopia ranged from 1 octave (at 1 year) to more than 2 octaves (at 4 1/2 years) below the mean visual acuity of the comparison group. Mean visual acuity scores for the few eyes in the retinal fold or partial detachment group that had quantifiable visual acuity were well below the means for the comparison group. CONCLUSIONS: Acute-phase retinopathy of prematurity that regresses without retinal residua produces no deficit in grating visual acuity between 1 and 4 1/2 years of age. In contrast, eyes with macular heterotopia show a visual acuity deficit, and the deficit is greater at older than at younger ages. Eyes with retinal fold or partial detachment that have measurable visual acuity show large visual acuity deficits at all ages.

Acute Disease↗