It is also known as a mydriatic, which means it dilates the pupil. Phenylephrine works by acting on alpha receptors on the muscle in the eye that dilates the pupil.
This causes this muscle to contract, which makes the pupil open up or dilate. This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately. Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby.
Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine. Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist. There may be some absorption of phenylephrine from the eye into the bloodstream.
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you treatment with this medicine is used. Similarly, check with your doctor or pharmacist before taking any new medicines while using this one, to make sure that the combination is safe. Phenylephrine eye drops should not be used in people taking the following medicines, because the eye drops may increase blood pressure:.
There are currently no other eye drops containing phenylephrine available in the UK. Last updated Parenting Mental health Healthy eating Conditions Follow. Type keyword s to search. What is it used for? Dilating the pupil to aid examination of the inside of the eyeball , eg the fundus and retina.
Dilating the pupil as part of a treatment programme for an eye condition. How does it work? How do I use it? In particular, two out of the 10 subjects were extremely sensitive.
For them, the accommodation was reduced by 5. Mordi and colleagues [ 10 ] analyzed the mydriatic and cycloplegic effects of either cyclopentolate 0. They included five subjects aged between 25 and 43 years. Two drops of PHCl were instilled separated by 2 minutes, and the monocular static and dynamic AR were assessed with an infrared optometer. A supplementary lens allowed an additional effective vergence of 0.
Target size was scaled so that the smallest detail of each target subtended the same visual angle at all object distances. The authors characterized the dynamic change in response to an abrupt change in target vergence in terms of two temporal parameters, the reaction time and the response time. The reaction time is defined as the time elapsing between the stimulus change and the start of the corresponding response, and the response time is the time taken to complete the response.
The reaction times were little influenced by the drug used. Nevertheless, both drugs increased the response time, with cyclopentolate having the larger effect. Besides, considerable intersubject variations in response characteristics were observed particularly with respect to the initial direction of response. Regarding the effects of the drugs upon the steady state response levels, both drugs had considerable effects, and these effects varied as a function of time.
According to the authors, this slope reduction was obviously closely related to the recession of the near point found by Garner et al. In an additional report, Mordi and coworkers [ 11 ] stated the conclusions of a different study to analyze the effect of the topical instillation of PHCl on accommodation. Factors considered in this study were iris colour and the influence of the prior application of a topical anesthetic proparacaine hydrochloride before PHCl instillation.
Baseline measurements of AA, refractive status, and pupil diameter were obtained before any drops were instilled in the eyes of 10 Caucasian subjects all within the age range of 20 to 26 years. Each subject received 1 drop of topical anesthetic in 1 eye.
Three minutes later the subjects were instilled with 1 drop of PHCl 2. The AA was measured while the subject wore the appropriate optical correction for his or her distance refractive error. Pupil size was measured under the same lighting conditions. The authors obtained that PHCl 2.
Besides, anesthetizing the cornea improves the ability of PHCl to dilate the pupil. The authors concluded that prior application of an anesthetic prolongs both the depression effect of PHCl on the accommodation and the mydriatic effect, in eyes with either lightly or more heavily pigmented irides. Two years later, the possible influence of PHCl in the activity of the ciliary muscle was studied using in vitro samples. By means of attaching strips of the meridional and circular portion of the ciliary muscle to a tension gauge in an organ bath they were able to monitor isometrically the effect of drugs added to the perfusion medium.
As a result, ciliary muscle from only three out of eight eyes relaxed in responses to PHCl. Later on, Gimpel et al. After the instillation of a single drop of PHCl 2. In the first dilation regimen, one drop of 0. In the second dilation regimen, one drop of 0. The authors tested also a reversal regimen to counteract the effects of the mydriasis, by instilling one drop of 0.
A total of 47 subjects participated in the study. Two accommodation levels were measured: 1 the reading distance and 2 the near-chart distance at which the letters began to blur. Those subjects who wore glasses were instructed to use them for all of the tests. However, tropicamide in combination with PHCl had significantly decreased the mean AA of the subjects, obtaining values of 0.
Measuring 40 minutes after reversal with thymoxamine resulted in a mean accommodation value of 1. Ten visually normal subjects participated in the study, in which monocular temporal AR were measured objectively using a continuously recording dynamic tracking infrared optometer. They used a visual Badal stimulus deflector system to change optically the vergence apparent distance of the accommodation stimulus, which allowed stimulus vergence to be modulated without changing stimulus size, position, or luminance.
The dynamics of the AR to sinusoidal 0. The authors obtained a significant increase in accommodative gain at low- and mid-temporal frequencies, although no significant difference in phase lag was detected. According to the authors, as an optimum balance between the parasympathetic and sympathetic control of accommodation is necessary to respond to temporal variations in target distance and to prevent adaptation after sustained near vision, these results suggested that the sympathetic component of the response is necessary to provide maximum negative accommodation.
In , Do and coworkers [ 15 ] measured subjectively the AA with the push-up technique and objectively with the Hartinger Coincidence Refractometer in a set of 10 subjects.
They also assessed accommodative dynamics with an infrared optometer PowerRefractor. Measurements were taken before and at minute intervals for 90 minutes after instillation of PHCl 2.
According to the authors, this is likely to occur due to mydriasis of the pupil and decreased depth of focus rather than sympathetic inhibition of the ciliary muscle. Regarding dynamic measurements, some subjects showed a decrease in peak velocity of accommodation, suggesting that PHCl should not be used to dilate the pupil when testing accommodative dynamics. Static and dynamic EW-stimulated AR were studied in five iridectomized rhesus monkeys before and after phenylephrine instillation.
This method allows for an AR that is not affected by pupil size or visual feedback and that can be rigorously controlled by stimulus amplitude, differentiating so effects of PHCl on the ciliary muscle versus effects due to secondary optical factors resulting from mydriasis.
After the baseline recordings, two doses of 0. The effects of PHCl on dynamic accommodation were established in terms of peak velocities of accommodation and disaccommodation. The authors of this study concluded that although there are individual differences before and after the instillation of PHCl, these differences are not systematic, and within the resolution of the methods there are no significant effects of PHCl on AA, dynamics, or RSA.
Therefore, adrenergic stimulation causes strong pupil dilation in noniridectomized monkey eyes but does not affect EW-stimulated AA or dynamics in anesthetized, iridectomized rhesus monkeys. Recently, in , Sarkar et al. The viewing was monocular while AR was recorded bilaterally. They measured a peak velocity of accommodation with no PHCl significantly larger than those with all three concentrations of PHCl, while the data for the three drug concentrations were not significantly different from each other.
Overall, their results indicated that PHCl had a small but statistically significant negative impact on the response magnitude and peak velocity of accommodation but not that of disaccommodation. There appeared to be no obvious interaction between drug concentration and pupil size on accommodative performance, suggesting that the pharmacological effect of PHCl and the optical effect of increased pupil diameter following PHCl instillation both contribute towards the reduction in accommodative performance.
According to the authors, the reduction in accommodative performance is modest and does not carry a large clinical significance, meaning that PHCl could therefore be used to achieve pupil mydriasis without dramatically hampering accommodation.
In the same year Richdale et al. They aimed to determine if, in response to topical administration of 2. Pupil size and accommodative function were also measured.
Proparacaine was used both to increase patient comfort and because application of proparacaine has been shown to increase the effect of PHCl, especially in patients with dark irides [ 11 ].
This finding suggests, according to the authors, that there is no physiological effect on the accommodative system due to the effect of PHCl. The last contribution to the field was dated Bernal-Molina and colleagues [ 18 ] tested the hypothesis that changes in accommodation after PHCl instillation are due to changes in optics and not to changes in the function of the ciliary muscle.
They studied the effect of PHCl both on static and on dynamic accommodation. The effect on static accommodation was assessed for 8 eyes by computing the stimulus-response curve from the wavefront obtained at different vergence. Measurements were taken with a custom-made optical system, and the authors computed the gain and phase of the dynamic responses.
AR was calculated taking into account the effects of higher-order aberrations minimum RMS refraction and without them paraxial refraction. For dynamic accommodation, the authors found a mean difference in the AR gain of 0. The authors concluded that whereas they found a clear, statistically significant decrease in AR after the instillation of PHCl, they did not find any effect on static and dynamic accommodation when higher-order aberrations were not taken into account in the calculation of AR.
According to the authors, as paraxial refraction depends mainly on the ciliary muscle, its function seems to be unaffected by PHCl according to their results. Therefore, differences in reported effects of PHCl may be due to the methods used to calculate the AR. First investigations suggested some loss of functional accommodation in the human eye after PHCl instillation. Subsequent research studies, based on different measurement procedures, obtained contradictory conclusions, causing therefore an unexpected controversy that has been spread almost to the present days.
This manuscript reviews the main research studies that have analyzed the effect of PHCl on the accommodative system of the human eye and summarizes their main conclusions, describing the different measurement procedures that have been used in each one.
All in all, it seems that the most accepted conclusion is that subjective measurements are affected by mydriasis produced by PHCl instillation, in the sense that the alterations measured on accommodation are likely to occur due to optical changes in the eye following pupil dilation.
On the contrary, objective methods, which are able to separate accommodation measurements from the optical effects of the pupil dilation on the perception of the image, conclude that PHCl instillation has no effect over the accommodative abilities of the human eye. The authors declare that there is no conflict of interests regarding the publication of this paper.
Esteve-Taboada et al. This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors.
Read the winning articles. Journal overview. Special Issues. Esteve-Taboada , 1,2 Antonio J. Academic Editor: Edward Manche. Received 31 Jul Accepted 26 Oct Published 07 Dec Abstract Accommodation is controlled by the action of the ciliary muscle and mediated primarily by parasympathetic input through postganglionic fibers that originate from neurons in the ciliary and pterygopalatine ganglia.
Introduction Accommodation is the change in optical power experienced by the crystalline lens when the ciliary muscle contracts, which allows the human eye to focus on near objects. Autonomic Control of Accommodation The human body is equipped with a special branch of the nervous system called the ANS, which automatically controls and regulates the internal organs without any conscious recognition by the organism.
Figure 1. Schematic diagram of both sympathetic and parasympathetic divisions from the autonomic nervous system, showing the main receptors and neurotransmitters involved in each case. Figure 2. Figure 3. Agonist versus antagonist behaviour. The agonist is not the natural substance, but it acts similarly occupying the receptors and activating them, imitating or even enhancing therefore the effect produced by the natural substance. On the contrary, an antagonist mimics the natural substance to take its place in the receptor, blocking thus the cellular activity.
Recession of the near-point averaging 0. No change of either the far point of accommodation or the dark focus was evident in the results. NPA was the closest distance to which a line target could be moved towards the eye without noticeable blur. RPA was determined with the laser optometer after 5 minutes in complete darkness. Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases.
If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines. Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur.
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:. The dose of this medicine will be different for different patients.
Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so. The amount of medicine that you take depends on the strength of the medicine.
Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine. If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses. Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
Keep from freezing. If eye pain or change in vision occurs or if redness or irritation of the eye continues, gets worse, or lasts for more than 72 hours, stop using the medicine and check with your doctor. Along with its needed effects, a medicine may cause some unwanted effects.
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