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Purpose: Patients with non-proliferative macular telangiectasia type 2 (MacTel) have ganglion cell layer (GCL) and nerve fibre layer (NFL) loss, but it is unclear whether the thinning is progressive. We quantified the change in retinal layer thickness over time in MacTel with and without diabetes., Methods: In this retrospective, multicentre, comparative case series, subjects with MacTel with at least two optical coherence tomographic (OCT) scans separated by >9 months OCTs were segmented using the Iowa Reference Algorithms. Mean NFL and GCL thickness was computed across the total area of the early treatment diabetic retinopathy study grid and for the inner temporal region to determine the rate of thinning over time. Mixed effects models were fit to each layer and region to determine retinal thinning for each sublayer over time., Results: 115 patients with MacTel were included; 57 patients (50%) had diabetes and 21 (18%) had a history of carbonic anhydrase inhibitor (CAI) treatment. MacTel patients with and without diabetes had similar rates of thinning. In patients without diabetes and untreated with CAIs, the temporal parafoveal NFL thinned at a rate of -0.25±0.09 µm/year (95% CI [-0.42 to -0.09]; p=0.003). The GCL in subfield 4 thinned faster in the eyes treated with CAI (-1.23±0.21 µm/year; 95% CI [-1.64 to -0.82]) than in untreated eyes (-0.19±0.16; 95% CI [-0.50, 0.11]; p<0.001), an effect also seen for the inner nuclear layer. Progressive outer retinal thinning was observed., Conclusions: Patients with MacTel sustain progressive inner retinal neurodegeneration similar to those with diabetes without diabetic retinopathy. Further research is needed to understand the consequences of retinal thinning in MacTel., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2025. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Background: Facial contour naturally decreases the visual field. Peripheral visual field defects caused by facial anatomy and ocular pathology can be missed in a routine standard of care. Mathematically calculating the true angle for turning the head to optimize the peripheral visual field has not been studied to date. The purpose of this study was to explore the utility of turning the head during perimetry to maximize the testable visual field., Methods: Six healthy study participants aged 18-52 were enrolled, prospectively; the dominant eye of each participant was tested. In total, 60-4 visual fields were obtained from each participant's dominant eye with the head in primary position. Then, the 60-4 tests were repeated with the head turned prescribed degrees toward and away from the tested eye ("manual method"). Based on a photograph of the participant's face, a convolutional neural network (CNN) was used to predict the optimal head turn angle for maximizing the field, and the test was repeated in this position ("automated method")., Results: Maximal visual field exposure was found at a head turn of 15° away from the tested eye using the manual method and was found at an average head turn of 12.6° using the automated method; maximum threshold values were similar between manual and automated methods. The mean of threshold in these subjects at the standard direction and the predicted optimum direction was 1,302, SD = 69.35, and 1,404, SD = 67.37, respectively ( P = 0.02)., Conclusions: Turning the head during perimetry maximizes the testable field area by minimizing the influence of prominent facial anatomy. In addition, our CNN can accurately predict each individual's optimal angle of head turn for maximizing the visual field., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 by North American Neuro-Ophthalmology Society.)

Prcis: Damage to disposable selective laser trabeculoplasty (SLT) lenses correlated with the amount of total laser energy. Furthermore, greater lens damage was associated with diminished patient treatment response., Purpose: Disposable SLT lenses have been observed to be damaged during use by laser, potentially affecting therapeutic response. This study sought to identify factors associated with the magnitude of lens damage and its effect on treatment outcomes., Patient and Methods: We analyzed 113 eyes from 82 patients who underwent SLT between 2020 and 2021 at an American academic medical center. For each procedure, we recorded baseline patient characteristics, procedure settings, physician age (as a possible factor causing laser defocus due to accommodation), and area of lens damage. Treatment response was calculated as the difference between preoperative and postoperative intraocular pressure (IOP)., Results: Area of lens damage was associated with greater total laser energy ( r =0.34, P <0.001) and greater mean energy per application ( r =0.37, P <0.001). IOP reduction decreased with increasing lens damage ( r =-0.19, P =0.022). Lens damage was not associated with patient characteristics indicative of glaucoma severity or user settings (physician age and slit lamp used). Greater IOP reduction was associated with higher preop IOP ( r =0.46, P <0.001) and a smaller cup-to-disc ratio ( r =0.22, P =0.036). IOP reduction was not associated with retinal nerve fiber layer thickness, patient age, or the number of glaucoma medications., Conclusions: Increased laser damage to disposable SLT lenses was associated with diminished treatment effect. The amount of damage was correlated with total and average laser energy, but not patient or physician factors. Overall, these findings call for reconsideration of using disposable SLT lenses as part of routine practice., Competing Interests: Disclosure: The authors declare no conflict of interest., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Purpose: To investigate the in vivo effect of scleral buckle surgery on ocular biomechanics and aqueous humor dynamics., Design: Prospective observational cross-sectional study., Participants: Nine patients with unilateral 360 degree encircling scleral buckles without vitrectomy for rhegmatogenous retinal detachments, between 3 and 39 months postoperative., Methods: All measurements were performed in both eyes of all participants. Intraocular pressure (IOP) was measured in the seated and supine positions using pneumatonometry. Outflow facility was measured using 2-minute weighted pneumatonography. Ocular rigidity coefficient was determined from the Friedenwald equations based on the difference in IOP with and without a weighted tonometer tip. The percentage change in IOP upon transitioning from seated to supine was calculated. Measurements for buckled and nonbuckled eyes were compared using paired Student t test of means., Main Outcome Measures: Sitting and supine IOP and percentage difference between the 2 positions; outflow facility; ocular rigidity coefficient., Results: Seated IOP was similar between buckled and nonbuckled eyes (16.1 ± 2.5 vs. 16.7 ± 2.7 mmHg; P = 0.5) whereas supine IOP was lower in buckled eyes compared with nonbuckled eyes (18.7 ± 2.6 vs. 21.3 ± 2.5 mmHg; P = 0.008). The percentage increase in IOP upon change in body position from seated to supine was greater in nonbuckled eyes (17.4 ± 9.4% vs. 27.6 ± 9.5%; P = 0.005). Ocular rigidity coefficient was lower in buckled (9.9 × 10 -3 ± 1.4 × 10 -3 μL -1 ) vs. nonbuckled eyes (14.4 × 10 -3 ± 3.1 × 10 -3 μL -1 ; P = 0.006). Outflow facility was not significantly different in buckled and nonbuckled eyes., Conclusions: Scleral buckling decreases ocular rigidity but does not affect outflow facility. This change in ocular biomechanics likely results in the attenuated IOP change from seated to supine position. Decreased ocular rigidity may also reduce IOP fluctuations and potentially reduce the risk for glaucoma progression., Financial Disclosure(s): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (Copyright © 2023 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objectives: Implementation of guideline-recommended depression screening in oncology presents numerous challenges. Implementation strategies that are responsive to local context may be critical elements of adoption and sustainment. We evaluated barriers and facilitators to implementation of a depression screening program for breast cancer patients in a community medical oncology setting as part of a cluster randomized controlled trial., Methods: Guided by the Consolidated Framework for Implementation Research, we employed qualitative methods to evaluate clinician, administrator, and patient perceptions of the program using semi-structured interviews. We used a team-coding approach for the data; thematic development focused on barriers and facilitators to implementation using a grounded theory approach. The codebook was refined through open discussions of subjectivity and unintentional bias, coding, and memo applications (including emergent coding), and the hierarchical structure and relationships of themes., Results: We conducted 20 interviews with 11 clinicians/administrators and 9 patients. Five major themes emerged: (1) gradual acceptance and support of the intervention and workflow; (2) compatibility with system and personal norms and goals; (3) reinforcement of the value of and need for adaptability; (4) self-efficacy within the nursing team; and (5) importance of identifying accountable front-line staff beyond leadership "champions.", Conclusions: Findings suggest a high degree of acceptability and feasibility due to the selection of appropriate implementation strategies, alignment of norms and goals, and a high degree of workflow adaptability. These findings will be uniquely helpful in generating actionable, real-world knowledge to inform the design, implementation, and sustainment of guideline-recommended depression screening programs in oncology., Trial Registration: ClinicalTrials.gov #NCT02941614., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To report a rare case of an intraretinal tuberculoma and associated neuroretinitis., Methods: The patient was evaluated with various imaging modalities including fundus photography, fluorescein angiography, magnetic resonance imaging, and optical coherence tomography; her extensive laboratory workup returned positive for tuberculosis., Results: After initially presenting with no light perception, 13 weeks of antitubercular therapy allowed for visual acuity recovery to 20/30., Conclusion: We demonstrate the spectral domain optical coherence tomography characteristics of an intraretinal tuberculoma.

Background: Eyes with a short axial length or anterior chamber depth often develop narrowed anterior chamber angles in association with an enlarging crystalline lens. We report a case of a patient who presented in angle closure, with a distant history of prior intervention for congenital cataracts and was presumed to be aphakic., Case Presentation: A 78-year-old male presented with acute onset unilateral eye pain and blurred vision. He was found to have increased intraocular pressure, anteriorly bowed iris, and angle closure. Despite prior documentation of aphakia after treatment for congenital cataracts, detailed workup revealed residual crystalline lens material pushing the peripheral iris anteriorly. Further history confirmed that the patient underwent a procedure in the 1940's to remove lens material centrally but was not truly aphakic. The patient was treated with anterior chamber paracentesis and intraocular pressure lowering drops. His intraocular pressure remains controlled with medical therapy alone., Conclusions: Patients that appear to be aphakic centrally may still present with angle closure secondary to residual peripheral lens material. This case highlights the importance of keeping this etiology on the differential in a patient with presumed aphakia., (© 2022. The Author(s).)

Objective: To evaluate whether a natural language processing (NLP) algorithm could be adapted to extract, with acceptable validity, markers of residential instability (ie, homelessness and housing insecurity) from electronic health records (EHRs) of 3 healthcare systems., Materials and Methods: We included patients 18 years and older who received care at 1 of 3 healthcare systems from 2016 through 2020 and had at least 1 free-text note in the EHR during this period. We conducted the study independently; the NLP algorithm logic and method of validity assessment were identical across sites. The approach to the development of the gold standard for assessment of validity differed across sites. Using the EntityRuler module of spaCy 2.3 Python toolkit, we created a rule-based NLP system made up of expert-developed patterns indicating residential instability at the lead site and enriched the NLP system using insight gained from its application at the other 2 sites. We adapted the algorithm at each site then validated the algorithm using a split-sample approach. We assessed the performance of the algorithm by measures of positive predictive value (precision), sensitivity (recall), and specificity., Results: The NLP algorithm performed with moderate precision (0.45, 0.73, and 1.0) at 3 sites. The sensitivity and specificity of the NLP algorithm varied across 3 sites (sensitivity: 0.68, 0.85, and 0.96; specificity: 0.69, 0.89, and 1.0)., Discussion: The performance of this NLP algorithm to identify residential instability in 3 different healthcare systems suggests the algorithm is generally valid and applicable in other healthcare systems with similar EHRs., Conclusion: The NLP approach developed in this project is adaptable and can be modified to extract types of social needs other than residential instability from EHRs across different healthcare systems., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Medical Informatics Association.)

Abstract: The Rho kinase inhibitor netarsudil is a recently approved therapeutic option for the management of increased intraocular pressure in the United States. Although phase 3 clinical trials noted corneal changes related to the medication-namely, nonvisually-significant corneal verticillata-descriptions of a unique form of cystic epithelial edema began to surface as netarsudil (and its sister drug ripasudil, approved in Japan) gained widespread use. This series adds 3 new cases and reviews the current literature on this unique side effect., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Importance: Implementation of guideline-recommended depression screening in medical oncology remains challenging. Evidence suggests that multicomponent care pathways with algorithm-based referral and management are effective, yet implementation of sustainable programs remains limited and implementation-science guided approaches are understudied., Objective: To evaluate the effectiveness of an implementation-strategy guided depression screening program for patients with breast cancer in a community setting., Design, Setting, and Participants: A pragmatic cluster randomized clinical trial conducted within Kaiser Permanente Southern California (KPSC). The trial included 6 medical centers and 1436 patients diagnosed with new primary breast cancer who had a consultation with medical oncology between October 1, 2017, through September 30, 2018. Patients were followed up through study end date of May 31, 2019., Interventions: Six medical centers in Southern California participated and were randomized 1:1 to tailored implementation strategies (intervention, 3 sites, n = 744 patients) or education-only (control, 3 sites, n = 692 patients) groups. The program consisted of screening with the 9-item Patient Health Questionnaire (PHQ-9) and algorithm-based scoring and referral to behavioral health services based on low, moderate, or high score. Clinical teams at tailored intervention sites received program education, audit, and feedback of performance data and implementation facilitation, and clinical workflows were adapted to suit local context. Education-only controls sites received program education., Main Outcomes and Measures: The primary outcome was percent of eligible patients screened and referred (based on PHQ-9 score) at intervention vs control groups measured at the patient level. Secondary outcomes included outpatient health care utilization for behavioral health, primary care, oncology, urgent care, and emergency department., Results: All 1436 eligible patients were randomized at the center level (mean age, 61.5 years; 99% women; 18% Asian, 17% Black, 26% Hispanic, and 37% White) and were followed up to the end of the study, insurance disenrollment, or death. Groups were similar in demographic and tumor characteristics. For the primary outcome, 7.9% (59 of 744) of patients at tailored sites were referred compared with 0.1% (1 of 692) at education-only sites (difference, 7.8%; 95% CI, 5.8%-9.8%). Referrals to a behavioral health clinician were completed by 44 of 59 patients treated at the intervention sites (75%) intervention sites vs 1 of 1 patient at the education-only sites (100%). In adjusted models patients at tailored sites had significantly fewer outpatient visits in medical oncology (rate ratio, 0.86; 95% CI, 0.86-0.89; P = .001), and no significant difference in utilization of primary care, urgent care, and emergency department visits., Conclusions and Relevance: Among patients with breast cancer treated in community-based oncology practices, tailored strategies for implementation of routine depression screening compared with an education-only control group resulted in a greater proportion of referrals to behavioral care. Further research is needed to understand the clinical benefit and cost-effectiveness of this program., Trial Registration: ClinicalTrials.gov Identifier: NCT02941614.

Minimally invasive glaucoma surgeries have become increasingly popular in recent years, with the iStent Inject trabecular micro-bypass device (Glaukos, Laguna Hills, CA) being a well-tolerated treatment option for mild to moderate glaucoma, available for placement at the time of cataract surgery. While there have been reports of hyphema in the immediate postoperative period, there is little information available regarding etiology and management of delayed-onset, recurrent hyphema following iStent Inject placement. We present a case of recurrent hyphema occurring after iStent Inject placement and describe successful management with surgical removal of the device. Since we observed a reflux of heme originating from the site of stent placement into the anterior chamber intraoperatively when the intraocular pressure was lowered, we hypothesize that placement of the device into a collector channel allowed for influx of heme when the intraocular pressure dropped below episcleral venous pressure., Competing Interests: Disclosure: The authors declare no conflict of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: A 42-year-old Algerian man presented for binocular oblique diplopia, hypersomnolence with drop attacks, bilateral hearing loss, and thoracic pain. He had a right thalamomesencephalic hemorrhage due to an underlying cavernous malformation treated with subtotal surgical resection. On neuro-ophthalmic examination, the patient had a left relative afferent pupillary defect and a right oculosympathetic efferent pupillary defect (i.e., Horner syndrome) in addition to other thalamomesencephalic eye and neurologic signs (right fourth nerve palsy, hearing loss, hemiparesis, and thalamic pain). Clinicians should recognize the localizing value of this unique constellation of mesencephalic afferent and efferent pupillary defects., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 by North American Neuro-Ophthalmology Society.)

A 16-year-old boy presented with acute unilateral painless vision loss associated with a central retinal artery occlusion. Subsequent studies revealed an atrial septal defect of 17 mm, which was closed via a cardioform septal occluder. [J Pediatr Ophthalmol Strabismus. 2019;56:e73-e75.]., (Copyright 2019, SLACK Incorporated.)

Purpose: To present a documented case of development of focal choroidal excavation (FCE) in non-neovascular age related macular degeneration (AMD)., Methods: An 86-year-old female with pachy-choroid was followed clinically for non-neovascular AMD. Successive optical coherence tomography (OCT) scans were reviewed with tracking software., Results: Over the course of follow-up development of a FCE adjacent to a pachy-vessel along with disappearance of the pachy-vessel was documented in OCT., Conclusions: This case is a documented development of FCE in an eye with pachy-choroid features. The possible mechanism in this scenario may be thrombosis of pachy-vessels., (© 2019 Iranian Society of Ophthalmology. Production and hosting by Elsevier B.V.)

An 84-year-old woman reported onset of headaches, diplopia, and blurred vision. On examination, she was found to have a left sixth nerve palsy and an incongruous right homonymous hemianopia. Brain MRI demonstrated a left petroclival meningioma, causing this unusual combination of clinical findings. The patient was treated with radiation therapy and has remained stable over 4 years of follow-up.

Purpose Silicone oil a burgeoning adjuvant in the treatment of uveal melanoma where it is used for tissue protection during I-125 brachytherapy. While risk factors in the development of radiation retinopathy (RR) have been identified, treatment modulation for high-risk patients has largely been overlooked. We seek to expand the literature on this subject by reporting outcomes of I-125 brachytherapy with silicone oil in a high-risk population in the community setting. Methods Five patients with uveal melanoma and at least one risk factor for RR development underwent iodine-125 (I-125) plaque brachytherapy with concurrent pars plana vitrectomy (PPV), silicone oil administration, and fine needle aspiration biopsy (FNAB). Plaque and silicone oil removal were performed after seven days. Minimum follow-up was 12 months. Results Follow-up ranged from 12 to 56 months. Macular radiation doses ranged from 12.55 to 141.5 Gy; the two eyes with the largest doses developed RR at 34 and 15 months as well as neovascular glaucoma (NVG). Surgical complications included one rhegmatogenous retinal detachment (RD) and an intra-operative vitreous hemorrhage with post-operative hyphema requiring additional intervention. Conclusion RR may be attenuated by silicone oil administration in patients with some risk factors. In tumors farther from the macula, this benefit is more readily apparent. Tumors located more posteriorly may not benefit from silicone oil administration considering postoperative complications and operating time. Patient demographics, tumor characteristics, and anticipated macular radiation dosage may help determine which patients can benefit from silicone oil and identify patient risks for adverse outcomes., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2019, Lyons et al.)

Significance: We investigated, for safety and awareness, ultraviolet and high-energy violet light-blocking protection provided by assorted types of eyewear. Ultraviolet and high-energy violet light-filtering efficiency varied and did not correlate with price or advertised claims. Standardization of methods and specifications for lens spectral transmission evaluation is recommended., Purpose: Studies have linked exposure of high-energy visible blue light to effect and damage on retinal epithelial cells, photoreceptors, and ganglion cells. "Blue light" is more accurately differentiated into "high-energy visible blue-violet light" and "circadian rhythm blue-turquoise light." This study measured and compared spectral transmission of ultraviolet and high-energy violet light of low-, medium-, and high-priced sunglasses., Methods: Sunglasses and lens blanks were obtained from the University of Texas Medical Branch Optical Shop and vendors. Groups were based on promotional, retail, designer sunglasses, or "blue blocker" lenses. The percent transmittance of ultraviolet/visible spectral scans (800 to 350 nm) was measured using an Agilent Cary 50 spectrophotometer. High-energy violet/blue light was defined as 400 to 450 nm., Results: Promotional sunglasses (tinted polycarbonate) blocked 100% ultraviolet and 67 to 99.8% high-energy violet blue light. Retail sunglasses filtered out 95 to 100% ultraviolet A and 67% high-energy violet light. The tested designer sunglasses varied widely in their optical transmissibility with respect to their ultraviolet A and high-energy violet light-blocking properties, with some not blocking ultraviolet A. Clear and colorless Kodak Total Blue provided maximal high-energy violet protection, whereas clear Essilor Crizal Prevencia provided less high-energy violet blocking between 400 and 450 nm., Conclusions: The ultraviolet and high-energy violet (400 to 450 nm) light-filtering efficiency varied between sunglasses and clear lenses and did not correlate with price or advertised claims. Standardization of methods and specifications for lens spectral transmission evaluation is recommended.

This case report highlights utilization of image-guided, percutaneous transorbital direct cavernous sinus puncture to embolize an anteriorly draining carotid cavernous fistula (CCF) when conventional transarterial and transvenous approaches were not feasible. An 86-year-old man with a known posterior draining CCF developed acute unilateral proptosis, pain, and vision loss ("red-eyed shunt"). Cerebral angiogram revealed the dural CCF to be draining anteriorly into partially thrombosed ophthalmic veins. After failed transarterial and transvenous attempts, a percutaneous transorbital approach was used to successfully embolize the fistula using the Onyx Liquid Embolic System according to the visual needle path generated by the Seimens Syngo iGuide. To our knowledge, this is the first reported case of percutaneous transorbital direct embolization of a CCF utilizing the Seimens Syngo iGuide.

Purpose: To report a case of myasthenia gravis presenting with a false localizing sign, a bilateral pseudo internuclear ophthalmoplegia., Observations: A 61 year-old male presented with a five-week history of painless binocular oblique diplopia that was associated with fatigue, vocal hoarseness and bilateral ptosis, the latter two of which worsened through the course of the day. Exam was remarkable for an apparent bilateral internuclear ophthalmoplegia (INO). MRI of the brain with and without contrast and MRA of the head and neck were within normal limits. Lab work was positive for anti-AChR binding, blocking, and modulating antibodies, as well as anti-striated muscle and anti-titin antibodies. The patient was initiated on therapy for myasthenia gravis., Conclusion and Importance: Although myasthenia gravis often presents with ptosis or diplopia, rarely patients may develop pseudo-INO secondary to extraocular muscle weakness. True INO occurs with damage to the medial longitudinal fasciculus, a myelinated tract of fibers that controls yoked horizontal eye movements. Clinicians should be suspicious of the false localizing sign of a pseudo-INO associated with myasthenia gravis when more common causes of INO have been excluded.

A healthy 31-year-old female presented with an elevated vascular lesion on the right lower eyelid margin. Histology results from excisional biopsy demonstrated a range of intradermally nested atypical melanocytes with negative staining for BRCA1-associated protein 1, confirming the diagnosis of Wiesner nevus. Wiesner nevi may be a cutaneous hallmark of the BRCA1-associated protein 1-associated cancer susceptibility syndrome, and to our knowledge, this is the first report of such a lesion presenting anywhere on the ocular adnexa.

Natural killer/T-cell lymphomas are extremely rare and carry high mortality rates. Epidemiologically, these cancers tend to affect mainly Asian and South American patients and are associated with Epstein-Barr virus seropositivity. This report details a 78-year-old Vietnamese woman who presented initially with vitritis of unknown cause, but later developed proptosis and conjunctival involvement as her disease spread. Biopsies of the orbit, ethmoid sinus, and conjunctiva were found to be significant for natural killer/T-cell lymphoma. The case highlights the diagnostic difficulty of this tumor given its rarity and ability to mimic other disorders.

A paramedian pontine stroke may herald the unique symptom of "salt and pepper" eye pain, in which patients describe the sensation of pepper rubbed into the eye. While localization of the lesion is a common thread among published cases, the mechanism for the sensation of eye pain is still a matter of conjecture. It is important for clinicians to be aware of this unique symptom because strokes rarely present with eye pain and failure to establish this diagnosis might lead to a poor clinical outcome.

Ring doves (altricial development) and Japanese quail (precocial development) were used as models to compare differences in serum free hormone concentrations and the binding of thyroid hormones to serum protein fractions in adults, and the pattern of free thyroid hormones in the serum of altricial vs. precocial young. Total and free hormones were determined directly by RIA; free hormones also were determined by equilibrium dialysis. Binding protein fractions were identified by electrophoresis of serum preincubated with labelel hormones. Albumin bound the largest proportion of T4 in serum to both species; albumin also bound the largest proportion of T3 in doves, but globulin bound the largest proportion in quail. There were significant differences between species in the proportional binding of both thyroid hormones by different protein fractions at physiological pH. Electrophoretic separations at alkaline pH significantly altered hormone binding by different protein fractions from that at physiological pH. These data explain some conflicting results in the literature on thyroid hormone-binding proteins in different species. Free T4 and free T3 were below the sensitivity limits of the assays during the perinatal period in doves. After hatching, serum free T4 rose more rapidly than total T4. After day 12, hormone concentrations decreased, with a proportionately greater change in free T4 than in total T4. Serum free T3 concentrations were variable, but did not change significantly during development. These results demonstrate that the pattern of serum free thyroid hormones, like that of total hormones, is markedly different in altricial than in precocial development.

The enzymatic nature of 5'-monodeiodination (5'-D) in avian liver homogenates was demonstrated by abolishment of activity by iopanoic acid (IOP). T3 production from T4 was dependent on enzyme and substrate concentrations, incubation time, incubation temperature, and pH. Two pathways of 5'-D activity were present in avian liver and exhibited characteristics similar to those described in mammalian tissues. Type II activity was identified as propylthiouracil (PTU)-insensitive activity. Type I (PTU-sensitive) was determined by difference between Total and Type II. Km values were 1.58 microM T4 for Total activity and 0.90 nM T4 for Type II, corresponding to the characteristics of the mammalian pathways. The effects of goitrogens on avian hepatic 5'-D were equivalent to those reported for the mammalian enzyme.