Effects of orbital decompression on duction, cyclotorsion and diplopia

BACKGROUND

Orbital decompression is commonly performed to correct proptosis in patients with Graves' orbitopathy (GO). In literature, the incidence of new-onset constant diplopia after orbital decompression varies. Few studies have evaluated changes in duction and cyclodeviation after orbital decompression. We evaluated the changes in duction, cyclodeviation, eye position and degree of diplopia after orbital decompression.

METHODS

We retrospectively analysed data from patients who underwent orbital decompression at our hospital between January 2016 and July 2020. Data regarding the type of decompression, eye position, duction, cyclodeviation and level of diplopia according to the Gorman score were recorded.

RESULTS

Data from 281 eyes/orbits of 156 patients were analysed. Proptosis decreased from 23.8±2.5 to 20.9±2.5 mm. Horizontal and vertical duction range decreased (horizontal d=0.40 and vertical 0.30; p=0.000) after surgery; however, the change was not clinically significant (≤5°). Horizontal deviation changed towards esodeviation (d=-0.45; p=0.000), whereas vertical deviation remained stable (d=0.15; p=0.161). Preoperative cyclotorsion in the primary and downgaze positions changed towards incyclodeviation (primary: d=0.30, p=0.021; downgaze d=0.30, p=0.039). Diplopia improved in 22% (18 patients), whereas new-onset constant diplopia developed in 11% (12 patients). Elevation has an excellent predictive value of causing new-onset constant diplopia when measured preoperatively as <19°, sensitivity 88.0%, specificity 41.7% (area under the curve 0.812 (95% CI 0.660 to 0.963); p=0.000).

CONCLUSION

After orbital decompression, incidence of new-onset constant diplopia was 11% and 22% of the patients had partial or complete improvement of their diplopia. The changes in duction, cyclodeviation and horizontal deviation showed a statistical but not clinical difference. Patients with GO and a preoperatively restricted elevation of <19° are at risk of developing new-onset constant diplopia. In addition, preoperative incyclodeviation may worsen after decompression surgery.

[Watery eyes: diagnostic and therapeutic considerations]

Tear complaints can arise from either an increased tear production or from a disturbed tear drainage. Increased tear production from the lacrimal gland is a neuroregulated response to a dried out or irritated ocular surface. Dryness often results from a reduced quality of the tear film, but can also be caused by eyelid malposition with increased globe exposure. Impaired tear drainage usually occurs when the lacrimal drainage system is blocked at the level of the ductus nasolacrimalis, the canaliculi or the lacrimal punctae. Anatomical knowledge of the lacrimal system is necessary to distinguish between the different causes. Using cases and illustrations, we provide insight into the diagnostic considerations for a patient with a watery eye.

Workflow and treatment results for computer-aided design and 3D-printed conformer therapy of congenital anophthalmia and microphthalmia

BACKGROUND/AIMS

To evaluate treatment with custom, three-dimensional (3D) printed conformers for socket expansion in congenital microphthalmia and anophthalmia (MICA).

METHODS

Retrospective analysis of prospective cohort from 2016 to 2020. All children received custom-made 3D-printed conformers increasing in size. We measured height, width, thickness, surface and volume of first and consecutive conformers, as well as horizontal palpebral fissure length (HPF) at start and follow-up visits. We analysed these parameters for severely (<45%) and moderately (>45%-75%) affected children, based on affected axial length on ultrasonography.

RESULTS

We included 18 cases (9 severe, 9 moderate) with a total of 174 conformers (88 severe, 86 moderate) and a mean follow-up of 2.8 years (range 1.3-4.8). The mean relative HPF increased from 77% to 93% with 16/17 cases reaching >80%, and 12/17 cases >90% symmetry. Horizontal and vertical conformer dimensions increased up to 10 months of treatment, with a steeper slope for the severe group (10.5% vs 5.5% for height and 9.0% vs 6.1% for width gain per treatment month, for severe and moderate MICA, respectively). After 10 months of treatment conformer height and width increased only slightly. No serious complications were observed.

CONCLUSION

3D-design and printing of solid conformers results in highly acceptable horizontal eyelid symmetry in the treatment of congenital MICA. The mean increase in conformer height and width in the first 10 months should be about 170% for moderate and about 200% for severe MICA. The presented conformer size formulas can aid ophthalmologists and ocularists to plan conformer treatment.

Three-Dimensional Computer-Aided Design of a Full-Color Ocular Prosthesis with Textured Iris and Sclera Manufactured in One Single Print Job

Three-dimensional (3D) printing of ocular prosthesis has been scarcely described in medical literature. Although ocular prostheses have been 3D printed successfully, iris colors are often manually added to the final product afterward. The objective was to produce a 3D-printed ocular prosthesis with textured iris and sclera in one single print job. We designed an average 3D model of an ocular prosthesis in 3D software, and took a high-resolution digital photograph of a human eye, which was processed in graphical software. By using functions called "displacement mapping" and "UV mapping" on the 3D model, the extent of height displacement was used to digitally produce a textured and colored iris and sclera on the 3D model. By using a polyjet 3D printer, different colors and materials could be used for different prosthesis components. We were able to design and 3D print a lifelike ocular prosthesis with realistic iris and sclera texture. The process took less than 4 h, of which 2.5 h are "printing time," reducing labor time compared with conventional methods. This proof-of-concept adds valuable knowledge to the future manufacture of 3D-printed ocular prostheses, which has several benefits over the conventional production method: 3D printing is much faster, reproducible, and prostheses can easily be digitally adjusted and reprinted. This study is an important step in the development of a full-fledged 3D workflow to produce lifelike custom eye prostheses.

Meta-analysis of ocular axial length in newborns and infants up to 3 years of age

In pediatric ophthalmology it is often necessary to obtain axial length in young children. For children older than 3 years, noncontact biometry can be used. For younger children this is usually not an option, and the clinician needs to rely on other imaging modalities. Depicted data curves in textbooks elaborate on few studies and limited number of subjects. The existing literature regarding normal axial length for preterm infants and term newborns is summarized and critically appraised for number of subjects, relevance, measurement method and error, gender and retinopathy of prematurity. We obtained axial length measurements for a total number of 6,575 eyes in 27 papers published from 1964 to 2018 (9 papers with 2,272 eyes for preterm children, 24 papers with 4,303 eyes for term children). Initially, axial length increases rapidly: from a mean 5.1-16.2 mm in week 12 to week 37 gestational age. From 38 weeks, growth rate decreases from 16.2 mm to a mean of 21.8 mm at 3 years old. Male infants have a larger average axial length than females at birth; the difference is 0.24 mm (95%CI: 0.15-0.33, P < 0.001). We present a useful growth curve and formula that may serve as a reference for diagnosing abnormal growth.

Recurrent contracted sockets treated with personalized, three-dimensionally printed conformers and buccal grafts

Purpose:

Recurrent contracted sockets are complex situations where previous surgeries have failed, disabling the wear of an ocular prosthesis. A combined method of surgery and long-term fixation using custom-made, three-dimensional (3D) printed conformers is evaluated.

Methods:

Retrospective case series of nine patients with recurrent excessive socket contraction and inability to wear a prosthesis, caused by chemical burns (n = 3), fireworks (n = 3), trauma (n = 2) and enucleation and radiotherapy at childhood due to optic nerve glioma (n = 1) with three average previous socket surgeries (range 2–6). Treatment consisted of a buccal mucosal graft and personalized 3D-printed conformer designed to be fixated to the periosteum and tarsal plates for minimal 2 months. Primary outcome was the retention of an ocular prosthesis. Secondary outcome was the need for additional surgeries.

Results:

Outcomes were measured at final follow-up between 7 and 36 months postoperatively (mean 20 months). Eight cases were able to wear an ocular prosthesis after 2 months. Three cases initially treated for only the upper or only the lower fornix needed subsequent surgery for the opposite fornix for functional reasons. Two cases had later surgery for cosmetic improvement of upper eyelid position. Despite pre-existing lid abnormalities (scar, entropion, lash deficiency), cosmetic outcome was judged highly acceptable in six cases because of symmetric contour and volume, and reasonably acceptable in the remaining two.

Conclusions:

Buccal mucosal transplant fixated with a personalized 3D-designed conformer enables retention of a well-fitted ocular prosthesis in previously failed socket surgeries. Initial treatment of both upper and lower fornices is recommended to avoid subsequent surgeries for functional reasons.

Classification for treatment urgency for the microphthalmia/anophthalmia spectrum using clinical and biometrical characteristics

PURPOSE

Current clinical classifications do not distinguish between the severity of the MICrophthalmia/Anophthalmia (MICA) spectrum with regard to treatment urgency. We aim to provide parameters for distinguishing mild, moderate and severe MICA using clinical and biometrical characteristics.

METHODS

We performed a single-centre, cross-sectional analysis of prospective cohort of 58 MICA children from September 2013 to February 2018 seen at the Amsterdam University Medical Center, The Netherlands. All patients with a visible underdeveloped globe were included. We performed full ophthalmic evaluation including horizontal palpebral fissure length, axial length by ultrasound and/or MRI measurements, paediatric and genetic evaluation. Cases were subdivided based on clinical characteristics. Biometrical data were used to calculate the relative axial length (rAL) and the relative horizontal palpebral fissure length (rHPF) compared with the healthy contralateral eye for unilateral cases.

RESULTS

In previously untreated patients, a strong correlation exists between rAL and rHPF, distinguishing between severe, moderate and mild subjects using rAL of 0-45%, 45-75% and 75%-100%, respectively. Clinical subgroups were randomly dispersed throughout the scatterplot.

CONCLUSION

Current classifications lack clinical implications for MICA patients. We suggest measuring eyelid length and axial length to classify the severity and determine treatment strategy. The 'severe' group has obvious asymmetry and abnormal socket configuration for which therapy should quickly be initiated; the 'moderately' affected group has normal socket anatomy with a microphthalmic eye with disturbing asymmetry for which treatment should be initiated within months of development; the 'mild' group has a slightly smaller axial length or less obvious eyelid asymmetry for which reconstructive correction is possible, but expansive conformer treatment is unnecessary.

Persistent socket pain postenucleation and post evisceration: a systematic review

PURPOSE

To investigate causes, diagnostics and treatment modalities for persistent socket pain (PSP) after enucleation and evisceration.

METHODS

A systematic search was undertaken in accordance with the PRISMA Statement, in PubMed, Embase.com and Thomson Reuters/Web of Science. We searched for relevant papers until the 28th of July 2016. Inclusion criteria were (1) patients with a history of enucleation or evisceration, (2) PSP, (3) report of the cause and/or used diagnostics and/or treatment modality, (4) full text in English, Dutch or Spanish language. Excluded were (1) review articles, (2) comments, and publications concerning, (3) nonhumans, (4) exenterated patients, (5) acute postoperative pain, or (6) periorbital pain without pain in the socket. Given the lack of high quality evidence from randomized controlled trials, we examined all available evidence from primary observational studies and assessed quality within this lower level of evidence.

RESULTS

A total of 32 studies were included. Causes of PSP found were prosthesis-related (n = 5), dry socket (n = 2), trochleitis (n = 3), compression of the trigeminal nerve (n = 2), implant-related (n = unknown), inflammation (n = 5), surgery-related (n = 4), neuromas (n = 8), malignant tumours (n = 3), psychiatric/psychosocial (n = 2), phantom pain (n = 149), rarer entities (n = 3) or unknown (n = 14). Nonsurgical treatments suffice for conditions as trochleitis, prosthesis-related pain, dry socket and for phantom pain. Other causes of pain may require more invasive treatments such as implant removal.

CONCLUSION

Careful history and examination can give some direction in the diagnostic procedure; however, PSP is probably multifactorial and the specific origin(s) may remain uncertain. Implant replacement can be an effective treatment. Studies to identifiy less invasive procedures are required.

Cosmetic results of enucleation and/or external beam radiation therapy in 195 retinoblastoma survivors

PURPOSE

To report the cosmetic outcome and late effects of enucleation and/or irradiation for retinoblastoma and to evaluate the role of orbital implants.

METHODS

Patients (age >4 years) enucleated and/or irradiated for retinoblastoma, visiting the hospital for routine follow-up (April 2013 to May 2015), were included in our cross-sectional study. Data were obtained via clinical records, questionnaires, physical measurements and standardized photographs. Two independent observers scored the cosmetic features: upper eyelid position, lower eyelid position, volume deficiency, and prosthesis motility and overall cosmetic appearance.

RESULTS

A total of 195 patients participated. Ptosis was seen in 45 (28.3%) patients, lower lid sagging in 45 (28.3%). Both complications were associated with the orbital implant; ptosis being more common with increasing implant size (5.6% without implant, 16.7% with small implant, 37.1% with medium implant and 76.9% with large implant) and lower lid sagging being more common in patients without implant (20% with implant versus 37.5% without). Volume loss of the superior sulcus was seen in 107 sockets (66.9%), most frequent in additionally irradiated patients (χ² (2) = 42.7, p < 0.001) and in patients without implant (χ² (2) = 11.92, p = 0.003). Prosthesis motility was better in patients with orbital implant, regardless of the size.

CONCLUSION

Minor late and potentially treatable effects were seen in patients with implant. Larger sized implants were associated with a higher incidence of ptosis; implant size did not affect subjective outcome with respect to volume or prosthetic motility. Treatment with EBRT had a less favourable outcome.

Case series: effect of dermis-fat implants in different late onset socket problems encountered in retinoblastoma patients

BACKGROUND

Cosmetic dissatisfaction, pain, and chronic discharge may present months till years after enucleation in patients operated because of retinoblastoma. If noninvasive treatment modalities are insufficient, socket reconstruction can be considered. In this study, we discuss the results of dermis-fat exchange to treat these problems.

METHOD

Four patients with late onset post enucleation socket problems with a request for treatment were included in this prospective study. Socket inspection was documented and pictures at baseline and at a follow-up of at least 6 months were taken. To quantify the problem 'pain', a VAS score at baseline and at follow up was used. For the problem 'cosmetic dissatisfaction' standardized questionnaires were used.

RESULTS

Two patients were included because of cosmetic dissatisfaction; one was included with chronic pain and one with chronic discharge. Reconstruction of the socket using autologous dermis-fat insertion was done in all four. In one of them, severe shrinking of the fat developed. This patient was treated with additional injectable fillers. Both of them, ultimately, had satisfactory results. Autologous fat transplantation also solved the problem of chronic discharge and pain in the two other patients.

CONCLUSION

Socket reconstruction by autologous dermis-fat exchange may solve different post enucleation socket problems. However, shrinking of the transplanted fat may occur and require additional procedures.

Discharge and infection in retinoblastoma post-enucleation sockets

Purpose

To investigate the causes and treatment options for socket discharge and infection in patients enucleated for retinoblastoma (Rb).

Methods

A questionnaire was filled out by (parents of) ocular prosthesis-wearing patients with a history of enucleation as treatment for Rb. We collected data on patients’ characteristics, cleaning habits of the prosthesis, frequency of socket irritation, discharge, and infection, and use of antibiotics. With ordinal logistic regression analysis, factors related to the outcome parameters (frequency of irritation, mucoid and purulent discharge) were identified. In a subset of young asymptomatic and symptomatic patients, a swab culture of the socket was performed to determine the presence of microorganisms.

Results

A total of 186 patients or their parents (mean age of the patients: 17.3 years, ranging from 0.8 to 88.3 years) filled out the questionnaire. Irritation, mucoid discharge, and purulent discharge were frequently (once a month or more often) experienced in 75 (39.5%), 127 (66.8%), and 15 (13.2%) sockets, respectively. Younger age was associated with a higher frequency of mucoid and purulent discharge. Radiation therapy, chemotherapy, gender, age at surgery, cleaning frequency, and nocturnal wear were not associated with the outcome parameters. In a subgroup of 26 patients, the sockets were swabbed and cultured. All symptomatic patients had a positive bacterial culture versus 15% (2/13) of the asymptomatic patients (P<0.001). Common cold was correlated with both symptoms and presence of bacteria. Haemophilus influenzae and Staphylococcus aureus were the species most frequently cultured.

Conclusion

Ocular prosthesis-wearing patients often experienced mucoid discharge, and less often irritation and socket infection. These complaints were found to decrease with increasing age, but did not seem to be influenced by cleaning or wearing habits. Symptomatic sockets, with and without discharge, were correlated with the presence of pathogenic bacteria for which local antibiotic treatment seemed effective in most cases.

Orbital implants in retinoblastoma patients: 23 years of experience and a review of the literature

PURPOSE

To evaluate complications of different types of orbital implants following enucleation for retinoblastoma.

METHODS

We performed a retrospective chart study of all patients that underwent enucleation as treatment of retinoblastoma between April 1991 and June 2013. Events of implant exposure, extrusion (defined as a complete loss of the implant, or a major exposure that could not be closed) and socket abnormalities were analysed for association with implant type and influence of additional external beam radiation therapy (EBRT) and/or chemotherapy.

RESULTS

A total of 224 enucleations in 216 patients (eight bilateral) were identified. Mean age at surgery was 1.9 (median 1.5) years. Of the 219 included enucleated eyes, 20 were not replaced by a primary implant and 18 were replaced by an Allen implant. Scleral wrapped hydroxyapatite (HA) and acrylic implants (polymethylmethacrylate) were inserted in, respectively, 79 and 102 cases. In the total population, 29 treatment or implant-specific events (13.2%) were registered. Main complications were implant exposure n = 10 (4.6%) and extrusion n = 6 (2.7%). The acrylic/sclera group had less exposures or extrusions (5 of 102, 4.9%) compared to the HA/sclera group (10 of 79, 12.7%), although this difference did not quite reach statistical significance (p = 0.06). Additional treatment (chemotherapy and/or EBRT for the fellow eye) was administered in 78 cases (35.8%). The overall complication rate in the entire study population was significantly higher (16.7% versus 5.7%) in the group exposed to additional therapy (OR 3.3; 95% CI 1.30-8.36 p = 0.008). This negative effect of additional therapy was also significant in the combined acrylic/HA group (OR 2.9; 95% CI 0.97-8.46 p = 0.048).

CONCLUSION

Our results suggest a favourable outcome for acrylic implants compared to the HA implant. Additional treatment with chemotherapy and/or EBRT is associated with an increased risk of complications.

3D Orbital Reconstruction in a Patient with Microphthalmos and a Large Orbital Cyst-A Case Report

BACKGROUND

Orbital cysts are rare developmental anomalies that can occur in microphthalmic and anophthalmic patients. Such cysts can promote orbital growth and subsequently markedly increase the size of the orbit, which is commonly underdeveloped in these patients. Cyst removal is therefore generally dissuaded (at least) in the first 5 years.

CLINICAL CASE

A 6-year-old boy with a microphthalmos and a cyst developed protrusion of his prosthetic eye and a swelling of the lower eyelid. MRI showed a large cyst causing distortion of the right orbit. Due to the expansive orbital growth and subsequent misfitting of the prosthesis, cystectomy and orbital floor reconstruction was performed using 3D technology.

CONCLUSION

3D imaging and printing enables exact delineation of orbital cysts and the adjacent bony structures. Furthermore it offers the possibility to plan an individual surgical approach and to design and fabricate a custom fit orbital floor implant.

Worldwide enucleation techniques and materials for treatment of retinoblastoma: an international survey

Purpose

To investigate the current practice of enucleation with or without orbital implant for retinoblastoma in countries across the world.

Methods

A digital survey identifying operation techniques and material used for orbital implants after enucleation in patients with retinoblastoma.

Results

We received a response of 58 surgeons in 32 different countries. A primary artificial implant is routinely inserted by 42 (72.4%) surgeons. Ten (17.2%) surgeons leave the socket empty, three (5.2%) decide per case. Other surgeons insert a dermis fat graft as a standard primary implant (n=1), or fill the socket in a standard secondary procedure (n=2; one uses dermis fat grafts and one artificial implants). The choice for porous implants was more frequent than for non-porous implants: 27 (58.7%) and 15 (32.6%), respectively. Both porous and non-porous implant types are used by 4 (8.7%) surgeons. Twenty-five surgeons (54.3%) insert bare implants, 11 (23.9%) use separate wrappings, eight (17.4%) use implants with prefab wrapping and two insert implants with and without wrapping depending on type of implant. Attachment of the muscles to the wrapping or implant (at various locations) is done by 31 (53.4%) surgeons. Eleven (19.0%) use a myoconjunctival technique, nine (15.5%) suture the muscles to each other and seven (12.1%) do not reattach the muscles. Measures to improve volume are implant exchange at an older age (n=4), the use of Restylane SQ (n=1) and osmotic expanders (n=1). Pegging is done by two surgeons.

Conclusion

No (worldwide) consensus exists about the use of material and techniques for enucleation for the treatment of retinoblastoma. Considerations for the use of different techniques are discussed.

Search for a correlation between telomere length and severity of retinitis pigmentosa due to the dominant rhodopsin Pro23His mutation

PURPOSE

Great variation exists in the age of onset of symptoms and the severity of disease at a given age in patients with retinitis pigmentosa (RP). The final pathway for this disease may involve apoptotic photoreceptor cell death. Telomere length is associated with biologic aging, senescence, and apoptosis. We evaluated whether the length of telomeres in leukocytes correlated with the severity of RP in patients with the Pro23His rhodopsin mutation who have shown marked heterogeneity in disease severity.

METHODS

We evaluated 122 patients with the Pro23His rhodopsin mutation. The patients' retinal function was stratified according to their 30-Hz cone electroretinogram (ERG). The length of telomeres in leukocytes was measured by the quantitative real time polymerase chain reaction (qRT-PCR) method in the 15 patients with the highest age-adjusted 30-Hz ERG amplitudes and in the 15 patients with the lowest amplitudes.

RESULTS

Mean leukocyte telomere length was similar in the 15 patients with the highest cone ERG amplitudes (median: 0.40 units; interquartile range 0.36-0.56) and the 15 patients with the lowest cone amplitudes (median: 0.41 units; inter quartile range 0.34 -0.64; p=0.95).

CONCLUSIONS

We found no evidence for an association between telomere length and the severity of RP as monitored by the cone ERG in patients with the Pro23His rhodopsin mutation.

Insights from retinitis pigmentosa into the roles of isocitrate dehydrogenases in the Krebs cycle

Here we describe two families with retinitis pigmentosa, a hereditary neurodegeneration of rod and cone photoreceptors in the retina. Affected family members were homozygous for loss-of-function mutations in IDH3B, encoding the beta-subunit of NAD-specific isocitrate dehydrogenase (NAD-IDH, or IDH3), which is believed to catalyze the oxidation of isocitrate to alpha-ketoglutarate in the citric acid cycle. Cells from affected individuals had a substantial reduction of NAD-IDH activity, with about a 300-fold increase in the K(m) for NAD. NADP-specific isocitrate dehydrogenase (NADP-IDH, or IDH2), an enzyme that catalyzes the same reaction, was normal in affected individuals, and they had no health problems associated with the enzyme deficiency except for retinitis pigmentosa. These findings support the hypothesis that mitochondrial NADP-IDH, rather than NAD-IDH, serves as the main catalyst for this reaction in the citric acid cycle outside the retina, and that the retina has a particular requirement for NAD-IDH.

Six Patients with Bradyopsia (Slow Vision)

OBJECTIVE

Recently, it was discovered that subjects who showed a prolonged response suppression on their electroretinogram (ERG) and had symptoms of photophobia, problems adjusting to bright light, and difficulties seeing moving objects shared a mutation in the RGS9 (regulator of G-protein signaling 9) gene that is involved in the deactivation of photoreceptor responses. The disorder was termed bradyopsia (slow vision). This paper reports the clinical presentation and long-term follow-up of 6 bradyopsia patients.

DESIGN

Retrospective observational case series with a follow-up ranging from 6 to 30 years.

PARTICIPANTS

Six patients with a homozygous mutation in the RGS9 gene.

METHODS

Clinical symptoms and signs were compared between the subjects and between their visits over time.

MAIN OUTCOME MEASURES

Symptoms, visual acuity (VA), ocular findings, visual fields, dark-adaptation tests, color tests, fluorescein angiography, and ERG findings.

RESULTS

Data showed a consistency in the individual symptoms and ERG recordings, but an extreme variation in VA between visits. Beside some irregularities in the macula in some patients, no other related eye abnormalities were seen. The low-to-subnormal VA varied with background luminance and typically increased by 2 to 3 lines when pinholes were used. Dark-adaptation tests, color tests, and fluorescein angiography were normal. Visual field tests showed a minor diffuse sensitivity loss. No progressive changes were seen over time.

CONCLUSIONS

No signs of progression were noted in the 6 bradyopsia patients. Photophobia, impaired movement perception, variable reduced VA that improved with the use of pinholes and ERG abnormalities were typical for the disease.

Retinitis pigmentosa

Hereditary degenerations of the human retina are genetically heterogeneous, with well over 100 genes implicated so far. This Seminar focuses on the subset of diseases called retinitis pigmentosa, in which patients typically lose night vision in adolescence, side vision in young adulthood, and central vision in later life because of progressive loss of rod and cone photoreceptor cells. Measures of retinal function, such as the electroretinogram, show that photoreceptor function is diminished generally many years before symptomic night blindness, visual-field scotomas, or decreased visual acuity arise. More than 45 genes for retinitis pigmentosa have been identified. These genes account for only about 60% of all patients; the remainder have defects in as yet unidentified genes. Findings of controlled trials indicate that nutritional interventions, including vitamin A palmitate and omega-3-rich fish, slow progression of disease in many patients. Imminent treatments for retinitis pigmentosa are greatly anticipated, especially for genetically defined subsets of patients, because of newly identified genes, growing knowledge of affected biochemical pathways, and development of animal models.

Retinitis pigmentosa

Hereditary degenerations of the human retina are genetically heterogeneous, with well over 100 genes implicated so far. This Seminar focuses on the subset of diseases called retinitis pigmentosa, in which patients typically lose night vision in adolescence, side vision in young adulthood, and central vision in later life because of progressive loss of rod and cone photoreceptor cells. Measures of retinal function, such as the electroretinogram, show that photoreceptor function is diminished generally many years before symptomic night blindness, visual-field scotomas, or decreased visual acuity arise. More than 45 genes for retinitis pigmentosa have been identified. These genes account for only about 60% of all patients; the remainder have defects in as yet unidentified genes. Findings of controlled trials indicate that nutritional interventions, including vitamin A palmitate and omega-3-rich fish, slow progression of disease in many patients. Imminent treatments for retinitis pigmentosa are greatly anticipated, especially for genetically defined subsets of patients, because of newly identified genes, growing knowledge of affected biochemical pathways, and development of animal models.

Night-vision goggles for night-blind subjects: subjective evaluation after 2 years of use

PURPOSE

To evaluate the usefulness of night-vision goggles (NVG) for night-blind subjects after 1 and 2 years of use.

METHODS

Eleven night-blind subjects with retinitis pigmentosa used NVG for a 2-year period. At the end of each year, they were requested to fill-in two questionnaires regarding their use of the instrument.

RESULTS

At both the 1- and 2-year evaluations, the subjects reported fewer problems with mobility in the dark when they used the goggles. At the 2-year evaluation, two individuals stated that they had stopped using the instrument, while seven used it at least twice a week. The nine subjects still using the instrument after 2 years reported an increase in their sense of independence and an increase in their potential for activities. The instrument was used most often during the dark winter season and for purposes such as visiting friends and family, travelling to work or sports, attending meetings and strolling.

CONCLUSION

At the 2-year follow-up, NVG were still being used by most of the night-blind subjects. Moreover, the device had a positive effect on the subjects' experienced opportunities and sense of independence. The instrument was considered useful in the daily lives of our subjects.

Improved mobility and independence of night-blind people using night-vision goggles

PURPOSE

To investigate whether the use of night-vision goggles (NVGs) by night-blind people improves their mobility and sense of independence under dark circumstances.

METHODS

Twenty night-blind subjects with retinitis pigmentosa were requested to walk predetermined routes at night with and without NVGs. The number of unintended contacts with obstacles (hits) and the percentage of preferred walking speed (PPWS) en route were assessed in three different situations: a darkened indoor corridor; a moderately lit outdoor residential area; and a well-lit outdoor shopping area. Assessments were performed before and after a 5-week training period, during which the subjects practiced using NVGs in their own surroundings, registered their experiences in a journal, and filled out questionnaires.

RESULTS

The mean number of hits in the darkened corridor declined from eight to two when NVGs were used. Mean PPWS (34%) did not improve. In the residential area, mean hits declined from eight to practically zero and mean PPWS increased from 60% to 72% (after training to 78%). In the shopping area, subjects walked at 93% PPWS without any hits and showed no improvement with NVGs. Subjective scores revealed a good sense of orientation, feelings of safety and tranquility and an increase in independent mobility when NVGs were used.

CONCLUSIONS

Using NVGs seems to improve nighttime mobility in dark outdoor conditions by decreasing unintended contacts with obstacles and increasing walking speed. Use of NVGs increased independent activities in these subjects and was generally positively evaluated for everyday outdoor use.