Variable Effects of Previously Untested Muscarinic Receptor Antagonists on Experimental Myopia
Bibliographic record
Abstract
PURPOSE: Atropine, pirenzepine, and himbacine prevent form-deprivation myopia (FDM) when administered intravitreously. The mechanisms and sites of action of these drugs against myopia are not clear. To shed further light on whether this mechanism is muscarinic, several other muscarinic antagonists were tested. METHODS: Various concentrations of atropine, pirenzepine, dexetimide, scopolamine, tropicamide, benztropine, dicyclomine, gallamine, mepenzolate, oxyphenonium, propantheline, procyclidine, 4-diphenylacetoxy-N-methylpiperidine (4-DAMP), hexahydro-sila-difenidol (HHSiD), p-fluorohexahydro-sila-difenidol (pf-HHSiD), methoctramine, AFDX-116, and quinuclidinyl benzilate (QNB) were injected into goggled eyes of Leghorn cockerels three times at 48-hour intervals. Fellow control eyes received saline. Control animals received saline in both eyes. Twenty-four hours after final injections, refraction, eye weight, and axial length were measured, and eyes were prepared for microscopy. RESULTS: Other than atropine and pirenzepine, only oxyphenonium caused full rescue from FDM (goggled versus control; mean +/- SD; refraction differences: -9.50 +/- 0.22 D vs. 0.83 +/- 0.31 D, P < 0.001; wet weight differences: 75.67 +/- 3.84 mg vs. 2.33 +/- 6.14 mg, P < 0.001; axial length differences: 0.80 +/- 0.05 mm vs. 0.03 +/- 0.04 mm, P < 0.001). Oxyphenonium-treated retinas showed no damage. Of the other compounds, several elicited partial rescue and/or damaged the retina, whereas others had no effect. CONCLUSIONS: Oxyphenonium prevents FDM in chicks. The ineffectiveness or partial effectiveness of other compounds, coupled with the high concentrations of effective compounds required to prevent FDM, suggests that muscarinic antagonists act to prevent FDM, either at sites distant from the retina, or through a nonmuscarinic mechanism, on which only some of these drugs act.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".