Eye structure

The immediate or secondary necrosis (by more progressive diffusion into depth or by concomitant toxic effect) explain the macroscopic lesions of the tissues of the various eye structures (eyelids, conjunctiva, cornea, even iris or the ocular lens) that are specific to the chemical bum. 

Parkinson, T.M., et al. 2000. The effects of in vivo iontophoresis on rabbit eye structure and retinal function. Invest Ophthalmol Vis Sci 41 S772. 

Eye. Atropine and similar antimuscarinics block the acetylcholine-mediated contraction of the pupillary sphincter muscle, thus causing dilation of the pupil (mydriasis).1 During an ophthalmologic exam, these drugs may be applied topically in order to dilate the pupil, thus allowing a more detailed inspection of internal eye structures such as the retina. 

Oyster, C. (1999). The cornea and sclera. In The Human Eye, Structure and Function, pp. 325-78. Sinauer Associates, Sunderland, MA. 

In addition to nanoaperture arrays, structured af>ertures could provide higher fluorescence rate enhancement than single apertures, while still enabling efficient signal-to-background discrimination. Examples include the bull s eye structures (56, 23), nanopockets (68) or combined slit and aperture (69). 

In the case of a bull s eye structure, the relative electromagnetic enhancement is about 100 (computed for an incoming plane wave and consistent with experiment (72)), but the structure radius and thus the laser beam focus spot are about 4 times the diffraction limit (minimum focus size). If we compare the relative intensity enhancement to the case of a diffraction-limited spot, the intensity with the bull s eye is increased by 100x(l/4) = 6.25, which is about the enhancement with a single (bare) aperture with a tightly focused beam. Of course, this argument has to be supplemented with the influence the emission rate and the directivity of the fluorescence beam, which contribute to the overall enhanced fluorescence. However,... 

Oyster CW (1999) The Human Eye Structure and Funcdon. Sunderland, Mass Sinauer Associates, Inc. 

Fig. 6.17 Liver metastasis (subcostal section) hypoechoic fringe (arrow) wide, more hyperechoic margin and hypoechoic central colliquation ( bull s-eye ). Structural inhomogeneity of the remaining hepatic segments...

However, a 6-month dog study showed liver toxicity at all doses above 5 mg kg May and a 1-year study established that above lmgkg day alachlor causes effects in the liver, spleen, and kidney. In 2-year rat studies, doses above 2.5 mg kg day caused irreversible degeneration of the iris and related eye structures. 

Inhalation and ingestion are harmful and may be fatal. The major effect from acute inhalation is CNS depression. It produces dizziness, tiredness, headache at lower concentrations (<1500 ppm), anesthesia in the range of 1500-3000 ppm, and may cause death at high levels (e.g., 40 000 ppm). A dose of 10 ml (14.8 g) of chloroform can cause CNS depression and death due to respiratory and cardiac arrest. The oral lethal dose is estimated to be between 0.5 and 5gkg (loz to 1 pint) for an average 70 kg man. Short-term inhalation of chloroform at 900 ppm can cause dizziness, fatigue, and headache. Skin contact may result in irritation and redness and high levels can cause sores. Eye contact with liquid chloroform may result in painful irritation of the superficial eye structures, burns, and may cause corneal necrosis and ulcers. 

Ideally, the surface of the transparent cover should have a gradient of the index of refraction ranging from 1.0 for air to the index of refraction of the cover material. For the required very small indices of refraction no materials exist in nature. Such small indices of refraction can only be made by effective media in which the cover material is mixed with air on a subwavelength scale as described in Sect. 1. Subwavelength surface-relief structures with a continuous profile as shown in Fig. 2 form an effective refractive index gradient and are therefore well suited for broadband AR surfaces. This type of AR surface-relief grating is called a moth-eye structure according to the example found in nature on the cornea of... 

Fig. 2 SEM picture of an artificial moth-eye structure originated in photoresist...

Marshall J, Cronin TW, Kleinlogel S (2007) Stomatopod eye structure and function a review. Arthropod Struct Dev 36 420 148... 

Figure 4. Sequence of snapshots frame A shows a homogenous phase (note that the black speckles are talcum particles used to trace motion on the gel). Transition to hexagonal patterns is shown in frames B D, followed by the formation of white-eye structures in E. Frames F-H show the subsequent transformation of the white-eye structures to honeycomb patterns. The arrows indicate the direction of particle motion in a single patch of the pattern. Temporal sequence after preparing the system A) 9 min, B) 9.5 min, C)10 min, D) 13 min, E) 17 min, F) 24 min, G) 26 min, H) 30 min.

Similarly as with the case above, the size and delicacy of eye structures require the use of microsurgical techniques when operating on this organ. Significant procedures here include vitreoretinal surgery, cataract surgery, and retinal vein cannulation. 

Titanium tetrachlorine (TiCI ) has a molecular weight of 189.7. NIOSH lists 10 mg/m as the lowest lethal concentration for mice by oral route of inhalation. It is highly corrosive and presents a special hazard because it reacts violently with water to liberate heat and produce hydrochloric acid. When it comes in contact with the skin, the chemical should be wiped dry. A splash of the liquid in an eye may lead to permanent eye structure damage. 

Dogs and cats can be used also, but the validity of this model must be checked every time as pointed out at the beginning of this paper. Eye structure and vascularization are different from those of man. When we make a review of recent literature on toxicology studies, we can observe that toxicity of intravitreal injected drugs on the retina are mainly studied in rabbits, but dogs and cats can also be used (Liverani ). 

Fig. 1. SEM picture of natural moth-eye structures (flour moth, Ephestia kuehniella). Fraunhofer ISE.

Fig. 2. SEM picture of an artificial moth-eye structure made at Fraunhofer ISE and illustration of the graded refractive index. The periods of the crossed grating are 250 nm each. Fraunhofer ISE.

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